DETAILED ACTION
The instant application having application number 18/136703 filled on 4/19/2023 has a total of 6 claims pending for examination. There are 1 independent claim and 5 dependent claims, all of which are examined below.
The application is entitled to the July 26, 2022 filling date through foreign priority to Chinese Patent Application No. 2022108872154.
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Drawings
The drawings were received on 04/19/23. These drawings are accepted.
Specification
The abstract of the disclosure is objected to because it exceeds the recommended 150-word limit. A corrected abstract of the disclosure is required and must be presented on a separate sheet, apart from any other text. See MPEP § 608.01(b).
Claim Objections
Claim 2 is objected to because the limitation “Ni is the number and number of acid fracturing fractures in Class i reservoir” unnecessarily repeats the term “number” and is grammatically incorrect. Correction is required.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 4 and 5 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 4 recites the phrase “h≥40 m”. There is insufficient antecedent basis for this limitation because claim 4 depends from claim 1 and 3, and neither recite the term “h”. Correction is required. For examination purposes, the term “h” will be interpreted as the horizontal length of the well.
Claim 5 recites the phrase “determined by S22”. There is insufficient antecedent basis for this limitation because claim 5 depends from claim 1, and it doesn’t not recite the term “S22”. Correction is required.
Claim Rejections - 35 USC § 101
35 U.S.C. 101 reads as follows:
Whoever invents or discovers any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions and requirements of this title.
Claims 1-6 are rejected under 35 U.S.C. 101 because the claimed invention is directed to an abstract idea without significantly more.
Step 1, Statutory Category:
Yes: Claims 1-6 are directed to a method.
Step 2A Prong I, judicial Exception:
The Examiner submits that the foregoing claim limitations constitute mental processes and mathematical concepts when given their broadest reasonable interpretation. Abstract ideas are bolded.
Claim 1 recites the limitations:
A three-dimensional acid fracturing method for carbonate reservoirs in long intervals, sequentially comprising the following steps:
S1: based on the distribution characteristics of porosity and permeability of the reservoir where the candidate well is located, the reservoirs are divided into Class I, Class II and Class III, and the required acid fracturing fracture density range ρir of different types of reservoirs is determined according to the increase of production;
S2: Determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year based on interval length of different types of reservoirs in candidate wells and acid fracturing fracture density range ρir determined by S1;
S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2;
S4: Based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined.
The limitation based on the distribution characteristics of porosity and permeability of the reservoir where the candidate well is located, the reservoirs are divided into Class I, Class II and Class III, and the required acid fracturing fracture density range ρir of different types of reservoirs is determined according to the increase of production recites a mental process under MPEP § 2106.04(a)(2)(III) because it can be practically performed in the human mind or with pen and paper through observation, evaluation, and judgment. For example, a person can review recorded porosity and permeability values and use evaluation and judgement to group reservoir intervals having similar characteristics into classes. The person can then review the production values associated with different fracture densities, compare the amount of production increase produced by each additional fracture, and identify when further increases in fracture density no longer create a substantial increase in production. Based on that comparison, the person can use evaluation and judgement to select the fracture density range that provides the desired production for each reservoir class.
The limitation determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year based on interval length of different types of reservoirs in candidate wells and acid fracturing fracture density range ρir determined by S1 recites an abstract idea because it is directed to mathematical concepts under MPEP § 2106.04(a)(2)(I), which includes mathematical relationships and mathematical calculations. The limitation requires using the interval lengths and fracture counts to determine the fracture density. The claim also requires calculating the fifth year NPV for the possible fracture numbers, comparing the calculated NPV values, and selecting the fracture number that produces the highest NPV. These steps also involve mathematical calculation, relationships between numerical variables, and optimization of a value (see MPEP § 2106.04(a)(2)(I)).
The limitation determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2 recites a mental process under MPEP § 2106.04(a)(2)(III) because it can be practically performed in the human mind or with pen and paper through observation, evaluation, and judgment. For example, a person can first review how the candidate well is constructed and the number of fractures that should be created. Then the person can use that information to evaluate the available fracturing options and select an arrangement for diving the well into sections that will create the desired number of fractures. Therefore, the limitation merely involves reviewing information and using judgement to choose an appropriate set up.
The limitation based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined recites a mental process under MPEP § 2106.04(a)(2)(III) because it can be practically performed in the human mind or with pen and paper through observation, evaluation, and judgment. For example, a person can observe the previously selected arrangement, evaluate/compare the available fracturing methods, and then use judgement to select the best suited method for treating the reservoir based on the arrangement.
Step 2A Prong II, Integration into a Practical Application:
Claim 1 recites the following additional claim limitations outside the abstract idea which only present general field of use:
A three-dimensional acid fracturing method for carbonate reservoirs in long intervals, sequentially comprising the following steps (general field of use, see MPEP § 2106.05(h))
Step 2B, Significantly More:
When considered individually or in combination, the additional limitations and elements of claim 1 do not amount to significantly more than the judicial exceptions. The claim merely limits the recited mathematical calculations and mental evaluations to the field of three-dimensional acid fracturing for carbonate reservoirs. The claim also does not recite any improvement to acid fracturing technology that meaningfully limits or transforms the abstract ideas. Therefore, the additional limitations do not provide significantly more than the judicial exception.
The limitations of claim 2 do not remove or change the abstract limitations identified in claim 1. Instead, they add further details to the same mathematical calculations and mental evaluations. The classification of the reservoirs into Classes I, II, and III continues to recite a mental process involving evaluation and judgement under MPEP § 2106.04(a)(2)(III). While, the density formula, growth rate formula, numerical comparisons, and selection of a fracture density range recite mathematical calculations and relationships under MPEP § 2106.04(a)(2)(I). The recitation of Eclipse reservoir numerical simulation software merely instructs that the calculations be performed using computer software. The claim does not specify how the software performs the calculation, any particular configuration of the software, or an improvement to reservoir simulation technology. Therefore, the software is merely used as a tool to perform the recited mathematical calculations and amounts to an instruction to apply the abstract idea using a generic computer (see MPEP 2106.05(f)). Therefore, claim 2 only provide more specifics of the abstract ideas recited in claim 1 and does not integrate the judicial exception into a practical application or add significantly more than the judicial exception. Accordingly, claim 2 is not patent eligible.
The limitations of claim 3 do not remove or change the abstract limitations identified in claim 1. Instead, they add further details to the same mathematical calculations and analysis. Claim 3 first uses the fracture density and reservoir interval lengths to calculate a possible range of fracture numbers. It then calculates the production and net present value (NPV) for each possible fracture number, compares the resulting NPV values, and selects the fracture number associated with the highest NPV. These formulas, calculations, comparisons, and numerical optimizations recite mathematical concepts under MPEP § 2106.04(a)(2)(I). The recitation of Eclipse reservoir numerical simulation software merely instructs that the production calculations be performed using computer software. The claim does not specify how the software performs the calculation, any particular configuration of the software, or an improvement to reservoir simulation technology. Therefore, the software is merely used as a tool to perform the recited mathematical calculations and amounts to an instruction to apply the abstract idea using a generic computer (see MPEP 2106.05(f)). Accordingly, claim 3 only provides more specific recitations of the abstract ideas identified in claim 1 and does not integrate the judicial exceptions into a practical application or add significantly more than the judicial exceptions. Therefore, claim 3 is not patent eligible.
The limitations of claim 4 do not remove or change the abstract limitations identified in claim 1 and 3. Instead, they provide more specific rules for determining the value of Ns used in the mathematical calculations of claim 3. Principle (1) is directed to mathematical concepts under MPEP § 2106.04(a)(2)(I), which includes mathematical relationships and calculations. The limitation defines a numerical relationship between the desired change in fracture number and the sign of Ns. Thus, the limitation merely specifics how a numerical variable is used in the calculation. Principle (2) recites a mental process under MPEP § 2106.04(a)(2)(III), which includes observation, evaluation, and judgment. The limitation requires reviewing the location and quality of reservoirs, determining whether higher-quality and poorer-quality reservoirs are adjacent or staggered, and selecting the fracture density required by the reservoir. For example, a person could review reservoir information, identify a Class I reservoir next to a Class III reservoir, and determine that fractures should be arranged using the fracture density for the Class III reservoir. Principle (3) recites a mental process under MPEP § 2106.04(a)(2)(III), which includes observation, evaluation, and judgment. The limitation requires reviewing reservoir information, determining whether a dense zone separates different reservoir types, comparing the thickness of the dense zones, and deciding where the fractures should be placed. For example, a person could observe through logs that a 45-meter dense zone separates two reservoir types and decide to distribute fractures on both sides of the dense zone. Accordingly, claim 4 only provides more specific recitations of the abstract ideas identified in claim 1 and 3 and does not integrate the judicial exceptions into a practical application or add significantly more than the judicial exceptions. Therefore, claim 4 is not patent eligible.
The limitations of claim 5 do not remove or change the abstract limitations identified in claim 1. Instead, they add mathematical calculations and mental evaluations for selecting a staged fracture distribution process. Step S31 is directed to mathematical concepts under MPEP § 2106.04(a)(2)(I), which includes mathematical relationships, formulas, equations, and calculations. Specifically, S31 applies numerical values for pressure, depth, diameter, flow rate, density, and gravity to the recited formula to calculate the maximum number of sliding sleeves Mmax. Step S32 includes both mathematical concepts and a mental process. Since, comparing Ne to Mmax and calculating their values involve observing mathematical relationships and performing mathematical calculations. The remaining limitations require reviewing whether the well includes downhole sectional tools and using the comparison result to select between sliding sleeves, a combination of sliding sleeves and temporary plugging or temporary plugging alone. These steps fit the mental process category under MPEP § 2106.04(a)(2)(III), which includes observation, evaluation, and judgment. For example, a person could review the well completion information, use past experience and judgement to determine that Ne is 12 and Mmax is 10, and decide that 10 sliding sleeves and 2 temporary plugging operations should be used. The recitation of sliding sleeves, temporary plugging, and acid fracturing does not integrate the abstract idea into a practical application. These limitations merely instruct that the mathematical calculations and mental evaluations be applied using known fracturing equipment and processes. The claim only selects the process and determines the number of operations to use, without requiring the equipment be operated or the formation be fractured. Thus, these limitations amount to no more than instructions to apply the abstract ideas in an acid fracturing environment (see MPEP 2106.05(f)). Claim 5 is not patent eligible.
The limitations of claim 6 do not remove or change the abstract limitations identified in claim 1. Step S41 is directed to mathematical concepts under MPEP § 2106.04(a)(2)(I) because it calculates the percentage of each reservoir type and compares the results with the recited 33% or 50% thresholds. Step S42 recites a mental process under MPEP § 2106.04(a)(2)(III) because it uses the reservoir classification from S41 to select an acid fracturing method and related operating parameters through evaluation and judgement. For example, a person could identify that the interval is dominated by a Class II reservoir and select pre-fluid acid fracturing with the recited fluid amount and proportions. Under the broadest reasonable interpretation, S42 determines the treatment plan but does not require that the selected treatment be physically carried out. Therefore, the recited fracturing method merely applies the abstract calculations and evaluations in an acid fracturing environment (see MPEP 2106.05(f)). Accordingly claim 6 does not integrate the judicial exception into a practical application or add significantly more. Claim 6 is not patent eligible.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-4 are rejected under 35 U.S.C. § 103 as being unpatentable over He et al., "Optimization Research of Effective Stimulation for Carbonate Reservoir and its Application," International Journal of Smart Home, vol. 10, no. 3, 2016, pp. 83-92 (hereinafter "He") in view of HUIYUN et al., Chinese Application CN112780237A (hereinafter "Huiyun "), and further in view of Oury et al., International Application WO2011157763A2 (hereinafter "Oury") and Guo et al., "An innovative concept on deep carbonate reservoir stimulation: Three-dimensional acid fracturing technology," Natural Gas Industry B, vol. 7, no. 5, 2020, pp. 484-497 (hereinafter "Guo")
Regarding Claim 1, Huiyun teaches S1: based on the distribution characteristics of porosity and permeability of the reservoir where the candidate well is located, the reservoirs are divided into Class I, Class II and Class III (“Divide the reservoir into multiple regions according to the porosity and permeability of the reservoir in the study area, each of the multiple regions corresponds to a grade…” and “For example, Table 1 is a corresponding relationship between porosity, permeability, and reservoir grade provided in the examples of this application. As shown in Table 1, when the porosity of a certain area is greater than or equal to 12% and the permeability is greater than 10mD (millidarcy), the grade of the area in the reservoir is I. When the porosity of a certain area is less than 12%, greater than or equal to 6%, and the permeability is less than 10mD and greater than 0.1mD, the grade of the area in the reservoir is II. When the porosity of a certain area is less than 6%, greater than or equal to 1.5%, and the permeability is less than 0.1mD and greater than 0.001mD, the level of the area in the reservoir is III. When the porosity of a certain area is less than 1.5% and the permeability is less than 0.001mD, the grade of the area in the reservoir is IV.”)(e.g., Huiyun, Detailed ways [0003] and [0005], Figure 1 Step 101, Table 1). Huiyun teaches dividing a reservoir into multiple regions based on porosity and permeability and assigning each region a grade, where Grades I through III are interpreted as the claimed Class I through III reservoirs.
Huiyun does not teach the required acid fracturing fracture density range ρir of different types of reservoirs is determined according to the increase of production; S2: Determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year based on interval length of different types of reservoirs in candidate wells and acid fracturing fracture density range ρir determined by S1; S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2; S4: Based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined.
However, He teaches S1: … and the required acid fracturing fracture density range ρir of different types of reservoirs is determined according to the increase of production (“For common 500m length horizontal wells, number of fracture segment was optimized for different formation permeability (see Figure 4 and Figure 5) … The simulation results show that, for a lower permeability reservoirs (the effective permeability is less than 0.1 ~ 0.3mD), single well productivity increase gradually with the increase of segment number, and substantially with linear tendency. As can be seen from the graph, with the effective permeability gradually increased, more and more well productivity can be gotten. But a turning point appeared with the change of segment number. For 0.5mD reservoirs, the turning point was about 5~6. For higher permeability reservoirs, the number of fractures needed was less and less (see Figure 5).When reservoir permeability is 1mD, the preferred number of fractures is 4-5. But if reservoir permeability is 3mD, this optimized number is 3-4. For even greater permeability reservoir, well productivity increased as the number of fractures.”)(e.g., He, Section 3.2). He’s determination of fracture number ranges over a fixed 500m interval is interpreted as determining fracture density ranges, while the well productivity is interpreted as production.
S2: … based on interval length of different types of reservoirs in candidate wells and acid fracturing fracture density range ρir determined by S1 (“Based on above simulation results, optimized fracturing treatment under different physical properties, formation thickness and horizontal section length were listed in Table 2.”)(e.g., He, Section 3.4 and Table 2). Because He determines the number of fractures for a known reservoir interval, a person of ordinary skill in the art would divide the fracture number by the interval length to express the result as fractures per unit length, which is the claimed density.
Neither He nor Huiyun teach S2: Determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year … S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2; S4: Based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined.
However, He in view of Huiyun, further in view of Oury teaches S2: Determine the most economical fracture number Ne when the economic net present value NPV of candidate wells reaches the maximum in the fifth year (“The present invention aims at improving the production of a mature natural gas or oil field. In the present embodiment, the production of oil field 1 is improved by identifying the place and timing where to drill new wells, and identifying which technology to use for each of the new wells (type of completion, vertical or horizontal, and if so which orientation)” and “In this context, improving the production of oil field 1 means maximizing the value of a gain function, which depends on the field production, well by well and, as appropriate, layer by layer. For instance, the gain function may be the Net Present Value (NPV) of the field over five years. For instance, a simplified approach is to compute the discounted value of the production and to subtract the investment (the cost of drilling new wells)”) (e.g., Oury, page 3 lines 26-30 and page 5 lines 7-12)
He in view of Huiyun, further in view of Oury does not teach S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2; S4: Based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined.
However, He in view of Huiyun, further in view of Oury and Guo teaches S3: Determine the three-dimensional acid fracturing segmented fracture arrangement technology according to the completion mode of the candidate well and the most economical fracture number Ne determined by S2 (“In high temperature and high pressure reservoirs, for wells with perforation completion … soluble temporary plugging balls can be used for temporary plugging and interlayer diversion [17]; for horizontal wells with liner completions, degradable fibers or degradable fibers & temporary plugging particles can be used for temporary plugging and diversion.”)(e.g., Guo, Section 4.3)
S4: Based on the segmented joint distribution technology of three-dimensional acid fracturing determined by S3, the three-dimensional acid fracturing method of reservoir is determined. (“First, the 3D-AF technology contains three basic connotations: (1) selecting the corresponding acid penetration technology according to reservoir types so as to realize sufficient reservoir stimulation on the plane; (2) creating complex acid-fracture volume with higher flow conductivity under high closed pressure; (3) deploying acid-fracture volume rationally along the long hole section so as to realize sufficient reservoir stimulation in the wellbore direction.”)(e.g., Guo, Abstract). The quote teaches that three-dimensional acid fracturing involves both arranging the acid fracture volumes along the long well section and selecting the acid penetration technology for the reservoir type. The arranged acid fracture volumes correspond to the segmented fracture arrangement determined in S3, while the selected acid penetration technology corresponds to the acid fracturing method determined in S4.
Before the effective filing date of the claimed invention, it would have been obvious to one of ordinary skill in the art, having the teachings of He, Huiyun, Oury, and Guo before him or her, to improve He’s carbonate reservoir fracturing design by using Huiyun to classify the reservoir intervals and determine the segment positions based on reservoir properties and barriers. The improvement would have further included evaluating He’s possible fracture numbers using the five-year net present value analysis taught by Oury to select the fracture number that provides the greatest economic return. The selected fractures would then have been arranged and implemented, using Guo’s three-dimensional acid fracturing technology, according to the reservoir type and completion mode of the candidate well.
A person of ordinary skill in the art would have looked to Huiyun, Oury, and Guo when improving He because the references address closely related problems involving the design and optimization of reservoir stimulation treatments for oil and gas wells. He is directed to optimizing the number, length, conductivity, and distribution of fractures in carbonate reservoirs to improve horizontal well productivity. Huiyun is similarly directed to determining the number and positions of horizontal well segments for acid fracturing based on reservoir properties and seepage barriers. Guo is also directed to carbonate reservoir stimulation and specifically addresses optimizing the quality and spatial distribution of acid fracture volumes along long well sections and selecting the appropriate acid fracturing technology. Oury is reasonably pertinent because it teaches selecting among alternative oil and gas development configurations based on predicted production, investment cost, and projected net present values. Therefore, the references are analogous because they are all directed to selecting and implementing reservoir development or stimulation configurations based on technical and economic factors that affect production.
A person of ordinary skill in the art would have been motivated to apply Huiyun to He’s method because He recognizes that complex reservoir types and strong heterogeneity affect fracturing performance and teaches selecting fracture parameters according to the specific formation conditions (e.g., He, Section 1 and 3). Huiyun provides a known way to account for those conditions by using porosity, permeability, gas saturation, and seepage barriers to determine more accurate segment positions, thereby allowing reservoir fluids to flow more effectively into the acid fractures and improving recovery.
A person of ordinary skill in the art would have been further motivated to apply Oury’s five-year net present value analysis to the He-Huiyun fracture optimization framework because using net present value and economic output comparisons to guide the execution of large-scale projects was a known technique. He expressly teaches that horizontal well productivity is a key parameter of economic evaluation and shows that adding inappropriate fractures may provide progressively smaller production increases (e.g., He, Section 2 and 3.2). Oury teaches the known technique of comparing oil and gas development alternatives by calculating the discounted value of predicted production, subtracting the required investment, and selecting the alternative that maximizes five-year net present value. Applying Oury’s technique to He’s different fracture numbers would therefore have been no more than using a known evaluation method for its established purpose of selecting the most economical production alternative. The combination would have yielded the predictable result of selecting the fracture number whose additional production justifies its additional treatment cost long term, rather than selecting the fracture number based on single event production data.
A person of ordinary skill in the art would have been further motivated to incorporate Guo into the He, Huiyun, and Oury framework to improve the entire fracture planning and implementation workflow. He and Huiyun determine the fracture density, fracture number, and segment positions based on reservoir conditions, while Oury identifies the fracture number that provides the best economic return. He expressly teaches that the optimized fracture parameters are used to develop the fracturing design and Guo teaches completing that design by arranging the acid fracture volumes along the long well interval and selecting the fracturing technology according to the reservoir type and completion conditions. The combination would therefore have predictably produced a workflow that selects a technically and economically suitable fracture arrangement and then implements that arrangement in a manner suited for the candidate well, thereby improving stimulation of the full reservoir interval.
Regarding Claim 2, He in view of Huiyun teaches S11: Based on the distribution characteristics of porosity and permeability of the reservoirs where the candidate wells are located, the reservoirs are divided into Class I, Class II and Class III, and the fifth-year production of different types of reservoirs with different acid fracturing densities is calculated by using Eclipse reservoir numerical simulation software, wherein the acid fracturing density is defined as: Pi=Ni/Li Wherein: ρi is the acid fracturing fracture density of Class i reservoir, strips/m; Ni is the number and number of acid fracturing fractures in Class i reservoir; Li is the interval length of Class i reservoir, m; i is the type i reservoir, dimensionless (“Based on numerical simulation, this study established reservoir, wellbore and fracture model through professional simulation software Eclipse.”, “For common 500m length horizontal wells, number of fracture segment was optimized for different formation permeability”, and “When reservoir permeability is 1mD, the preferred number of fractures is 4-5. But if reservoir permeability is 3mD, this optimized number is 3-4”) (e.g., He, Section 2 and 3.2). Huiyun supplies the classification of the reservoir intervals based on porosity and permeability, while He teaches using Eclipse to compare production for different fracture numbers at different reservoirs permeabilities over a known 500m horizontal interval. Although He does not expressly write the claimed equation, He necessarily discloses the same relationship provided by both the number of fractures and the corresponding interval length. Fracture density represents the number of fractures distributed over a unit of length. Therefore, each fracture number tested by He necessarily has a corresponding density obtained by dividing that fracture number by the 500m interval length. He’s comparison of production for different fracture numbers over the fixed interval therefore inherently constitutes a comparison of production at different fracture densities. When He’s permeability specific results are applied to the reservoir classes taught by Huiyun, the preferred fracture numbers provide corresponding fracture density ranges for each reservoir class.
The remaining portion of claim 2 contains allowable subject matter, as explained in the Allowable Subject Matter section below.
Regarding Claim 3, He in view of Huiyun, further in view of Oury and Guo (as shown above) teaches S21: According to the interval lengths l1, l2 and l3 of different types of reservoirs, estimate the number range of acid fracturing fractures required by candidate wells Wherein: Ncp is the number range of acid fracturing fractures required by candidate wells; i is the type i reservoir, dimensionless; Ns is the number of fractures that need to be locally increased or decreased according to the distribution of reservoir types of candidate wells, bar (“For common 500m length horizontal wells, number of fracture segment was optimized for different formation permeability … When reservoir permeability is 1mD, the preferred number of fractures is 4-5. But if reservoir permeability is 3mD, this optimized number is 3-4”) (e.g., He, Section 3.2 and Table 2). This mapping works because He teaches determining a preferred fracture number range based on reservoir permeability and horizontal section length. When considered with Huiyun’s division of the candidate well into different reservoir classes and determination of a fracture density range for each class, He supports estimating and combining the fracture numbers required for the different reservoir intervals. The claimed summation is therefore a numerical expression of the fracture number determination taught by the combined references. Guo section 4 further teaches adjusting the quantity and location of acid fractures according to the distribution of different reservoir types and the presence of tight zones or flow barriers. Guo therefore supports locally increasing or decreasing the estimated fracture number when the actual reservoir distribution requires a different fracture arrangement, as represented by Ns.
S22: According to the number range Ncp of acid fracturing fractures required by S21 candidate wells, use Eclipse reservoir numerical simulation software to calculate the production of candidate wells with different acid fracturing fractures in five years, and calculate the economic net present value NPV of candidate wells with different fracturing fractures in the fifth year according to the following formula Wherein: NPV is the economic net present value of the fifth year when the number of acid fracturing fractures in candidate wells is N, ten thousand yuan; Fj is the difference between the cash inflow and outflow in the j year, RMB 10,000; r is the discount rate of reservation, %; Cj is the cost generated in the production process of oil and gas wells in the j year, RMB 10,000; qNj is the oil and gas production in the j year when the number of acid fracturing fractures is N, m3; sj is the commodity rate of oil and gas in the j year, %; ej is the oil and gas price in the j year, RMB 10,000/m3; C0 is the initial investment cost, RMB 10,000; When the economic net present value NPV reaches the maximum, the corresponding number of acid fracturing cracks is the most economical number Ne. (“A field simulator is a computer program capable of predicting a production of the oil field 1 as a function of a given scenario” and “In this context, improving the production of oil field 1 means maximizing the value of a gain function, which depends on the field production, well by well and, as appropriate, layer by layer. For instance, the gain function may be the Net Present Value (NPV) of the field over five years. For instance, a simplified approach is to compute the discounted value of the production and to subtract the investment (the cost of drilling new wells). In this case, for a given scenario, the gain function is …”)(e.g., Oury, page 4 lines 9-10 and page 5 lines 7-30). Oury evaluates different production scenarios using a field simulator and selects the scenario having the greatest five-year net present value. In the claimed method, each tested scenario is a candidate well having a different fracture number N. Oury’s simulator calculated production Pi therefore corresponds to qNj, which is the yearly production of the candidate well when it has N fractures. Oury’s net oil sale price after tax S corresponds to the economically realizable oil and gas value represented by the commodity rate sj multiplied by the oil or gas price ej. Oury’s discount rate d corresponds to the claimed discount rate r. Oury’s investment made during year j (lij) corresponds to the annual cost Cj, while the cost of drilling or initially implementing the candidate scenario corresponds to the initial investment C0. Thus, Oury teaches calculating the five-year economic value of each simulated production scenario using price, discount rate, annual costs, and initial investment in order to select the scenario with the maximum NPV. When the alternative scenarios are the different fracture numbers identified in S21, the fracture number producing the maximum NPV corresponds to the claimed most economical fracture number Ne.
Regarding Claim 4, He in view of Huiyun, further in view of Oury and Guo (as shown above) teaches the three-dimensional acid fracturing method for carbonate reservoirs in long intervals according to claim 3, characterized in that the determination of Ns follows three principles: (1) When the number of cracks needs to be increased, Ns takes a positive value, and when the number of cracks needs to be reduced, Ns takes a negative value (“The simulation results show that, for a lower permeability reservoirs (the effective permeability is less than 0.1 ~ 0.3mD), single well productivity increase gradually with the increase of segment number, and substantially with linear tendency ... For higher permeability reservoirs, the number of fractures needed was less and less (see Figure 5)...”)(e.g., He, Section 3.2 and Table 2). He teaches determining whether the initially estimated fracture number should be increased or decreased based on the simulated production response. For lower permeability reservoirs, He teaches that productivity increases “substantially with linear tendency” as the number of fracture segments increases and thereby supports an increase in the estimated fracture number. In contrast, He teaches that higher permeability reservoirs require “less and less” fractures and thereby supports a decrease in the estimated fracture number. Under the broadest reasonable interpretation, the positive and negative values of Ns merely identify the direction of these disclosed adjustments. An increase from the initially estimated fracture number is a positive Ns adjustment, while a decrease is a negative Ns adjustment.
(2) When high-quality reservoirs and poor-quality reservoirs are adjacent to or staggered with each other, the fractures are arranged according to the acid fracturing fracture density required by poor-quality reservoirs, in which the reservoir quality from good to bad is: Class I reservoir, Class II reservoir and Class III reservoir (“For example, Table 1 is a corresponding relationship between porosity, permeability, and reservoir grade provided in the examples of this application. As shown in Table 1, when the porosity of a certain area is greater than or equal to 12% and the permeability is greater than 10mD (millidarcy), the grade of the area in the reservoir is I. When the porosity of a certain area is less than 12%, greater than or equal to 6%, and the permeability is less than 10mD and greater than 0.1mD, the grade of the area in the reservoir is II. When the porosity of a certain area is less than 6%, greater than or equal to 1.5%, and the permeability is less than 0.1mD and greater than 0.001mD, the level of the area in the reservoir is III…”, “For example, the grades in multiple areas of the reservoir are I, II, III, and IV in order. The simulation is carried out according to the combination of Ⅲ+Ⅳ+Ⅲ, that is, two Ⅲ areas are deployed on both sides of the Ⅳ area to simulate the worst seepage conditions in the reservoir, and the Ⅳ and two Ⅲ areas are The geological information is input into the Eclipse software, and the Eclipse software establishes the acid-fractured seepage geological model in the form of "Class III + IV + Class III", and then obtains the acid-fractured seepage geological model from the Eclipse software.”, and “the higher the reservoir permeability, the faster pressure propagates in the reservoir and thus the less fracture segments demanded.”)(e.g., Huiyun, Detailed ways [0005] and [0012], He Section 3.3). Huiyun teaches ranking reservoirs according to porosity and permeability, with Grade I having the highest reservoir quality, followed by Grades II-IV. These grades are interpreted as the claimed Class I-III. Huiyun also teaches an arrangement in which a poorer reservoirs interval is positioned between and adjacent to better reservoir intervals.
(3) When there is a dense zone division between different types of reservoirs and the thickness of the dense zone is more than or equal to h≥40 m, the fractures are distributed on both sides of the dense zone respectively. If the dense zone needs to be distributed separately, the number of fractures is one. (“According to the distribution range of the horizontal section of the level IV area in the reservoir where the well is located, as shown in Figure 3, the simulated well length of the level IV area is 40m, and the corresponding reservoir production degree is 5% . As shown in Figure 4, the simulated well length of the grade IV area is 30m, and the corresponding reservoir production degree is 10%. As shown in Figure 5, the simulated well length of the grade IV area is 20m, and the corresponding reservoir production degree is 55%. As shown in Figure 6, the simulated well length of the grade IV area is 10m, and the corresponding reservoir production degree is 88%. At this time, the threshold range of the degree of reservoir production can be 0-30%. When the well direction length of the level IV area on the horizontal section is greater than 30m, the seepage barrier area needs to be considered when segmenting. According to the porosity, permeability, and gas saturation distribution of the well section to be segmented in the well, combined with the above-mentioned seepage barrier area, the number of segments and the location of the segments are determined... Considering the distribution of the seepage barrier zone and the length of the well direction, the reservoirs with high gas content and similar physical properties are concentrated into one section. After that, the segment position is determined in the middle of the seepage barrier area, and finally the number of segments of the well is 5 segments. They are 5300-5450m, 5450-5600m, 5600-5800m, 5800-5950m, 5950-6150m. In addition, after the segmentation is determined, the "packer + sliding sleeve" method can also be used to achieve segmentation and exploitation of the well.” and “When L≥2Lsb, the well direction position of the area with the highest grade is determined as the segmented position of the first well section, that is, the seepage barrier area is considered at this time, and the seepage barrier area is divided into one section”) (e.g., Huiyun, Detailed ways [0027] and [0032-0034]). Huiyun’s Class IV seepage barrier is interpreted as the claimed dense zone, and its disclosure length of 40m satisfies h≥40 m. Placing the segment position in the middle of the barrier using packer + sliding sleeve segmentation is interpreted as arranging the fracture segment on both sides of the dense zone. Dividing the seepage barrier into one section is interpreted as separately distributing the dense zone with one fracture.
Allowable Subject Matter
Claims 2, 5, and 6 contain allowable subject matter.
Regarding claim 2, the following portion is considered allowable subject matter, specifically S12, in combination with the remaining claimed limitations:
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He in view of Huiyun, further in view of Oury and Guo, teaches classifying reservoir intervals according to reservoir quality, evaluating production under different fracture arrangements, considering the economic performance of treatments, and adjusting the number and location of fractures according to reservoir heterogeneity. However, these references do not teach calculating, for each reservoir class, the fifth-year production growth rate by comparing production at a selected fracture density with production at the minimum fracture density according to the formula recited in S12. The other cited prior art, either alone or in combination with He, Huiyun, Oury and Guo, also do not teach using that calculated production growth rate to determine the required acid fracture density range for each reservoir class.
Claim 2 would be allowable if rewritten or amended to overcome the rejections under 35 U.S.C 101 and 35 U.S.C 103 rejections to claim 1, as set forth in this office action.
Regarding claim 5, the following portion is considered allowable subject matter:
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He in view of Huiyun, further in view of Oury and Guo, teaches selecting a fracture number, arranging fractures based on reservoir conditions, and using sliding sleeves or temporary plugging during staged acid fracturing. As per claim 5, He, Huiyun, Oury, Guo, and the other cited prior art, either alone or in combination, do not teach calculating the maximum number of sliding sleeves Mmax based on the required injection displacement and well head pressure limit according to the formula in step S31. The cited prior art also does not teach comparing Mmax with the most economical fracture number Ne and using that comparison, together with the completion mode of the well, to select the specific staged fracture distribution process recited in step S32.
Claim 5 would be allowable if rewritten or amended to overcome the rejections under 35 U.S.C 101, 35 U.S.C 112, and 35 U.S.C. 103 rejections of the parent claim 1, as set forth in this office action.
Regarding claim 6, the following portion is considered allowable subject matter:
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He in view of Huiyun, further in view of Oury and Guo, teaches classifying reservoir regions according to porosity and permeability, considering the lengths and distribution of the classified regions, determining an economical fracture arrangement, and selecting acid fracturing treatments based on the reservoir characteristics. The other cited prior art, either alone or in combination with He, Huiyun, Oury and Guo, does not teach calculating the proportion of each reservoir type within the interval, applying the claimed 33% or 50% thresholds to identify the dominate reservoir type, and then selecting the recited Class I, Class II, or Class III treatments based on the determination. Specifically, the combination of prior art references does not disclose the claimed turning acid, pre-fluid, and two stage alternating treatments together with their specific injection rates, acid quantities, and working fluid proportions.
Claim 6 would be allowable if rewritten or amended to overcome the rejections under 35 U.S.C 101 and 35 U.S.C 103 rejections to parent claim 1, as set forth in this office action.
Conclusion
The prior art made of record, listed on PTO-892, and not relied upon is considered pertinent to applicant's disclosure.
Bratton et al., “The Nature of Naturally Fractured Reservoirs,” Oilfield Review, vol. 18, pp. 4-23, 2006, teaches classifying naturally fractured reservoirs based on porosity and permeability and using the characteristics of each class to guide well stimulation/completion designs. This reference is pertinent because the applicant’s disclosure similarly uses reservoir classifications and fracture characteristics to plan fracture stimulation.
Yan et al., “Comparative Study of Discounted Cash Flow and Energy Return on Investment: Review of Oil and Gas Resource Economic Evaluation,” Finance Theory and Practice, vol. 24, no. 2, 2020, teaches economically evaluating oil and gas development projects by calculating net present value from projected cash inflows, development costs, an evaluation period, and a discount rate. Yan further explains that NPV is used to determine whether a proposed development is economically beneficial and demonstrates how changes in production related revenues and costs affect the calculated value. This reference is pertinent to applicant’s disclosure because it provides the economic framework for comparing proposed reservoir development arrangements and selecting the arrangement that produces the greatest NPV.
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/AREEBAH FATIMA/Examiner, Art Unit 2189
/REHANA PERVEEN/Supervisory Patent Examiner, Art Unit 2189
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