If the Notice of Pre-AIA or AIA Status
Claim 1 is currently presented for Examination.
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Response to Amendment
The amendment filed on 11/12/2025 has been entered and considered by the examiner. By the
amendment, claim 1 is amended and claims 2-6 are cancelled. Following Applicants amendments, the new matter rejection is added in view of amendment made. The 101 rejection of the claim 1 is withdrawn. The claim includes steps: "injecting fracturing fluid with a high viscosity into the selected working area" to achieve "hydraulic fracturing". This links the mathematical "solution" directly to a specific physical choice, which typically qualifies as a practical application rather than a generic "apply it" instruction. The claims are directed to a concrete method of hydraulic fracturing that uses finite-element stress modeling of rock formations to determine fracture initiation and injection of fracturing fluid. The 103 rejection of the claim is modified in view of amendment made. See office action for detail.
Applicant arguments 103 rejection
Applicant once again traverses the rejections, and specifically traverses the Examiner's contention that Soliman, by teaching 'optimal'? conditions for fracturing between 0 and 800 feet teaches that optimal spacing of fractures is 0.5-0.02 meters. No artisan would read a suggestion of 0-800 feet as an optimal range of 0.5-0.02, and the Examiner is surely aware of this. Moreover, to the extent that Soliman teaches any range of fracture dimensions, these are not taught in the context of Applicant's claimed method. No artisan would link the range of 0-800 feet allegedly taught as an 'optimum' by Soliman to the specific range of 0.5-0.02 meters in the context of the method disclosed by Applicant. Nothing taught by da Silva, Huang or Soliman would lead an artisan to reproduce Applicant's innovative methods. Accordingly, the rejections should be withdrawn.
Examiner response
Examiner respectfully disagrees. Examiner again maintained the same response back from last office action date 08/12/2020. The Examiner is utilizing the principle of overlapping ranges. Under established patent examination guidelines (such as MPEP 2144.05), if a claimed range falls within a range disclosed in the prior art, a prima facie case of obviousness is typically established. As shown in fig 11-12 of Soliman teaches fracture length 0-800ft and width 0-1inch. The claimed fracture length is 0.5 meters. This converts to approximately 1.64 feet. Soliman teaches ranges of fracture lengths from 0 to 800 feet. Therefore, the claimed fracture length of 1.64 feet falls within the reference's teachings. The claimed fracture width is 0.02 meters. This converts to approximately 0.79 inches. Soliman teaches ranges of fracture widths from 0 to 1 inch. Therefore, the claimed fracture width of 0.79 inches falls within the reference's teachings. Regarding the distance between the two fracture tips, Soliman teaches the required fracture tip length of 1.64 feet (or 0.5m) that also falls within the taught range of 0 to 800 feet. Thus, the rejection is still maintained.
Specification objection
The specification is objected to because it describes predicting fracture initiation based on a comparison between maximum shear stress and shear modulus of the reservoir with providing a technical explanation or supporting analysis for this relationship. (See [0012], [0027], [0052], [0069] and [0075]). Specially, the specification states that fracture initiation occurs when the maximum shear stress exceeds the shear modulus; however, shear modulus is a material stiffness parameter and is not generally recognized as a fracture initiation or failure criterion in rock mechanics or fracture mechanics. The specification does not explain how shear modulus functions as a threshold for fracture initiation, nor does it describe the conditions, assumptions or equations under which such as comparison would be valid. Accordingly, clarification or correction is required to render the disclosure clear and technically consistent.
Claim Rejections - 35 USC § 112, First Paragraph
4. The following is a quotation of the first paragraph of 35 U.S.C. 112(a):
(a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention.
The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112:
The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
5. Claim 1 is rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention.
a. Claim 1 recites the limitation “wherein, injection points and volumes of fracking fluid are selected based on the prediction to maximize fracturing efficiency”. The applicant did not identify support for this limitation and the examiner did not find it in the specification.
b. Claim 1 recites the limitation “selecting a work area for injection if conditions are favorable for rock fracture initiation; injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area.”. The applicant did not identify support for this limitation and the examiner did not find it in the specification. The disclosure fully supports predicting fracture initiation and providing prediction results; however, it does not expressly disclose selecting a work area for injection if conditions are favorable for rock fracture initiation; injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area. Para [0003] merely describe conventional hydraulic fracturing background and does not disclose performing fracturing fluid injections as part of the claimed invention.
c. Claim 1 recites “obtaining rock fracture data shear modulus”. However, the specification does not describe obtaining, measuring or acquiring shear modulus as rock fracture data. While para [0052] and several other paragraphs refers shear modulus of the reservoir as a threshold for fracture initiation, the disclosure does not explain how shear modulus is determined or incorporated into the method. Thus, the specification fails to reasonably convey possession of the claimed limitation.
Claim Rejections - 35 USC § 112, Second Paragraph
6. 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.
7. Claim 1 is rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AlA), 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 pre-AlA the applicant regards as the invention.
a. The claims have numerous issues with antecedent basis. The Examiner suggests amending the claims such that the first recitation of each distinct element uses articles such as “a”/”an”, later recitations referring back to the same distinct element uses articles such as “the”/”said”, to use disambiguating modifiers (e.g., first, second, etc.) when there are multiple distinct elements with the same base term, and that the use of modifiers for each distinct element is kept consistent. Below is a non-exhaustive list of examples of these issues:
i. Claim 1 recites the limitation "the fractures in the reservoir". Since this is the first mention, and "a plurality of fractures." It would be appropriate to use one term in order to avoid antecedent basis for this limitation. Appropriate correction is needed.
ii. Claim 1 recites the limitation "predicting whether the fracture will initiate." It is unclear if this refers to one of the "two fractures" from the model or a physical fracture in the working area.
iii. Claim 1 recites the limitation “the rock” near the end. It should be first introduced "a rock" or refer to the "rock in the reservoir" to establish what rock.
b. The claim employs terms of degree that lack an objective standard for measurement in the claim itself.
i. Claim 1 recites the term "high viscosity": The term "high" is a relative term. Without a specific numerical range or an objective standard defined in the specification, a person of ordinary skill in the art (PHOSITA) cannot determine what level of viscosity is required to avoid infringement.
ii. Claim 1 recites the term "conditions are favorable": This is a subjective term. Whether conditions are "favorable" depends on the subjective judgment of the user rather than an objective technical threshold.
c. The claim recites a result to be achieved rather than the specific steps necessary to attain it.
i. Claim recites the limitation “maximize fracturing efficiency”. This is a functional limitation that describes a goal rather than a distinct step. Claiming a result without the corresponding structure or acts to achieve it fails to clearly define the boundaries of the invention.
ii. Claim recites the limitation “thus obtaining hydraulic fracturing of the working area” which merely states an intended result without clearly reciting the steps that achieve the result.
d. Claim 1 recites ""stress states of special units." The term "special units" is not a standard term in the art of finite element modeling. Without further definition, its scope is indeterminate, making it impossible for the public to know what units are encompassed by this limitation.
e. The claim alternatively uses “working area” and “work area” which creates uncertainty as to whether the same or different elements are referenced.
f. Claim 1 recites “...when the highest value of the maximum shear stresses…is greater than the shear modulus of the reservoir…”. Shear modulus is a material stiffness parameter that defines relationship between shear stress and shear strain. It is not a failure criterion or limiting stress. A person of ordinary skill in the art would not understand how comparing a stress value to a modulus value determines fracture initiation. According, it is unclear how the recited comparison is to be performed or applied rendering the claim indefinite.
Claim Rejections - 35 USC § 103
8. In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
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.
9. 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.
10. This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
11. Claim 1 is rejected under 35 U.S.C. 103 as being unpatentable over da Silva, Bruno Gonçalves, and Herbert H. Einstein. "Finite element study of fracture initiation in flaws subject to internal fluid pressure and vertical stress." International Journal of Solids and Structures 51.23-24 (2014): 4122-4136.) hereinafter Silva in view of Huang et al. "Natural fractures initiation and fracture type prediction in coal reservoir under different in-situ stresses during hydraulic fracturing." Journal of Natural Gas Science and Engineering 43 (2017): 69-80.) hereinafter Huang and further in view of Soliman et al. (PUB NO: US 20150204175 A1)
Regarding claim 1
Silva teaches a method for hydraulic fracturing comprising the following steps: predicting initiation of rock fracture by: (see abstract- Hydraulic fracturing is a method used routinely in oil and gas exploitation and in engineered geothermal systems. The study showed that the ratio between the water pressure applied in the flaws and the vertical load/ stress (WP/VL) plays a crucial role in the magnitude and shape of the stress field around a flaw tip, and therefore in the location of tensile and shear fracture initiation. As WP/VL increases, the location of initiation of new tensile fractures shifts from the upper face of the studied flaw towards the region right ahead of the flaw tip; simultaneously, the location of initiation of new shear fractures shifts from the region ahead of the flaw tip to the upper face of the analyzed tip.) comprising the following steps:
obtaining rock fracture data, wherein the obtaining rock fracture data includes acquiring lengths, and distribution orientations of the fractures; (See page 4123-The main goal of this study is to numerically analyze the effect of the ratio between a vertical load, or stress, and the hydraulic pressure applied in existing flaws on the stress field in the vicinity of the flaw tips. These flaws intend to explicitly simulate a pair of fractures present in a rock formation. This numerical study should give one a solid basis not only for understanding the initiation of new fractures but also of their eventual propagation and coalescence, particularly in experiments currently being conducted by the authors of this paper on molded gypsum, granite and marble specimens. For this purpose, a double flaw geometry 2a-30-30 (as illustrated in Fig. 1) was modeled in ABAQUS. Fig. 1. Geometry 2a-30-30 and parameters used to describe double-flaw geometries. L is the ligament length, which is the distance between inner flaw tips expressed in terms of half flaw length a = 1/4 inch in the current study; β is the angle that the flaws make with the horizontal; α is the angle that the direction of the ligament between inner tips makes with the axes of the flaws. (In the 2a-30-30 geometry, both α and β are 30°).)
adopting a finite element software to establish a double fracture model based on the fracture data; (see page 4123-The main goal of this study is to numerically analyze the effect of the ratio between a vertical load, or stress, and the hydraulic pressure applied in existing flaws on the stress field in the vicinity of the flaw tips. These flaws intend to explicitly simulate a pair of fractures present in a rock formation. This numerical study should give one a solid basis not only for understanding the initiation of new fractures but also of their eventual propagation and coalescence, particularly in experiments currently being conducted by the authors of this paper on molded gypsum, granite and marble specimens. For this purpose, a double flaw geometry 2a-30-30 (as illustrated in Fig. 1) was modeled in ABAQUS, and different vertical stresses and internal flaw pressures were applied to the model. The variation of the maximum principal stresses and maximum shear stresses around the flaw tips were analyzed and related to fracture initiation. The numerical analysis was performed with the Finite Element code ABAQUS. The geometry modeled was a 2a-30-30, following the convention described in Fig. 1. The 2a-30-30 geometry was selected for two reasons: (1) the authors intend to compare the numerical results presented in this paper with experiments (which include rock specimens with the double flaw geometry 2a-30-30)
using the finite element software to establish a slab model, (see abstract- The main goal of this study is to numerically analyze the effect of the ratio between a vertical load, or stress, and the hydraulic pressure applied in existing flaws on the stress field in the vicinity of the flaw tips. For that purpose, a double flaw geometry 2a-30-30 was modeled in the Finite Element code ABAQUS, and different vertical loads and internal flaw pressures were applied to the model. The variation of the maximum principal stresses and maximum shear stresses around the flaw tips were analyzed and related to fracture initiation. See page 4123- The numerical analysis was performed with the Finite Element code ABAQUS. The geometry modeled was a 2a-30-30, following the convention described in Fig. 1. The ABAQUS models showing the boundary conditions and the mesh used are shown in Fig. 2.)
implanting two fractures in the slab model, wherein the two fractures are parallel to each other (see fig 1 The numerical analysis was performed with the Finite Element code ABAQUS. The geometry modeled was a 2a-30-30, following the convention described in Fig. 1.)
and are distributed at a 45 inclination, (see page 4124- Element 3 is oriented in the direction of maximum shear stress, which is rotated 90° from the principal directions, in the Mohr circle, or 45° when the actual Element 3 is compared with Element 2. For Element 3)
by meshing the slab model and fracture peripheries and fracture tips, establishing the double fracture model. (See page 4123-The main goal of this study is to numerically analyze the effect of the ratio between a vertical load, or stress, and the hydraulic pressure applied in existing flaws on the stress field in the vicinity of the flaw tips. These flaws intend to explicitly simulate a pair of fractures present in a rock formation. This numerical study should give one a solid basis not only for understanding the initiation of new fractures but also of their eventual propagation and coalescence, particularly in experiments currently being conducted by the authors of this paper on molded gypsum, granite and marble specimens. For this purpose, a double flaw geometry 2a-30-30 (as illustrated in Fig. 1) was modeled in ABAQUS. Fig. 1. Geometry 2a-30-30 and parameters used to describe double-flaw geometries. L is the ligament length, which is the distance between inner flaw tips expressed in terms of half flaw length a = 1/4 inch in the current study; β is the angle that the flaws make with the horizontal; α is the angle that the direction of the ligament between inner tips makes with the axes of the flaws. (In the 2a-30-30 geometry, both α and β are 30°). see page 4135-It should be noted that only fracture initiation is being modeled in this study. Modeling of propagation and coalescence of fractures would require implementing a remeshing algorithm and fracture initiation criteria in the Finite Element code used, or otherwise the use of other numerical methods, such as a Boundary Element code.)
that includes a stress a stress state analysis of a three-dimensional Mohr circle, comprising circles C1, C2 and C3 that represent stress state analysis of special units(see fig 3 and section 2.1)
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Examiner note: Fig 3 illustrates a Mohr circle with three distinct stress states corresponding to three special units: a general stress state, a principal stress state and a maximum stress state. These stress states correspond to claimed circles C1, C2 and C3 representing stress states or special units.
applying confining pressures of different strata to a boundary of the double fracture model to change stress differences of horizontal confining pressures and obtain different horizontal stress differences; (see page 4123-4124-The main goal of this study is to numerically analyze the effect of the ratio between a vertical load, or stress, and the hydraulic pressure applied in existing flaws on the stress field in the vicinity of the flaw tips. These flaws intend to explicitly simulate a pair of fractures present in a rock formation. For this purpose, a double flaw geometry 2a-30-30 (as illustrated in Fig. 1) was modeled in ABAQUS, and different vertical stresses and internal flaw pressures were applied to the model. The ABAQUS models showing the boundary conditions and the mesh used are shown in Fig. 2. The elements along the two vertical boundaries were limited to move in the vertical direction only, while the elements in the bottom horizontal boundary were fixed. Since the vertical edges of the model are constrained of moving horizontally, i.e. εx = 0 in these boundaries, and since by linear elastic theory εx = (σx-νσy)/E, then σx=νσy. In these expressions, σy and σx are the vertical and horizontal stresses, respectively, while εx is the horizontal strain. Therefore, the vertical boundaries of the model are subject to a horizontal stress equal to 0.28σy. While varying the horizontal stress would produce changes in the stress field around the flaws. For a given Mohr circle, three elements are represented in Fig. 3 showing different normal and shear stress combinations: Element 1 is oriented along its horizontal and vertical axes and is therefore submitted to generic normal and shear stresses; Element 2 is oriented along the principal axes I and II and consequently is subject to the maximum principal stress, which is tensile, to the minimum principal stress ; and to no shear stress; Element 3 is oriented in the direction of maximum shear stress, which is rotated 90° from the principal directions, in the Mohr circle, or 45° when the actual Element 3 is compared with Element 2. For Element 3, the normal stresses are similar to each other. It should be noted that, for the purpose of this study and following ABAQUS convention, tensile stresses are considered positive, the x or 1-axis is horizontal, the y or 2-axis is vertical and the z or 3-axis is out-of-plane.)
according to the different horizontal stress differences, analyzing the corresponding three-dimensional stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip as the horizontal stress differences change, and obtaining a stress state at the fracture tip and both sides of the fracture; (see page 4123-4124-For this purpose, a double flaw geometry 2a-30-30 (as illustrated in Fig. 1) was modeled in ABAQUS, and different vertical stresses and internal flaw pressures were applied to the model. The variation of the maximum principal stresses and maximum shear stresses around the flaw tips were analyzed and related to fracture initiation. And see fig 3-For a given Mohr circle, three elements are represented in Fig. 3 showing different normal and shear stress combinations: Element 1 is oriented along its horizontal and vertical axes and is therefore submitted to generic normal and shear stresses; Element 2 is oriented along the principal axes I and II and consequently is subject to the maximum principal stress σI, which is tensile, to the minimum principal stress σII, and to no shear stress; Element 3 is oriented in the direction of maximum shear stress, which is rotated 90° from the principal directions, in the Mohr circle, or 45° when the actual Element 3 is compared with Element 2. For Element 3, the normal stresses are similar to each other (σ11=σ22). It should be noted that, for the purpose of this study and following ABAQUS convention, tensile stresses are considered positive, the x or 1-axis is horizontal, the y or 2-axis is vertical and the z or 3-axis is out-of-plane. See also fig 6-7)
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predicting whether the fracture will initiate by the stress state at the fracture tip and both sides of the fracture, wherein when the highest value of the maximum shear stresses at the fracture tip and both sides of the fracture is greater than the shear modulus of the working area of the reservoir, or the highest value of the maximum principal stresses at the fracture tip and both sides of the fracture is greater than the compressive strength of the working area of the reservoir, it is predicted that the fracture will initiate, (see page 4125-4126-It should be noted that when both tensile and shear fractures may initiate, the fracture that will prevail is the one that first reaches the micro-scale strength of the material (tensile or shear strength for tensile or shear fractures, respectively). The maximum principal stresses are mainly tensile around the existing flaws, as shown in Fig. 6. For the inner tip of the left flaw, the highest tensile principal stress occurs in the upper face of the flaw, near the flaw tip. This is, therefore, the location of tensile crack initiation for this loading condition. The dark gray region in Fig. 6 indicates compressive maximum principal stresses, which means that both principal stresses are compressive. Under these circumstances, tensile fractures cannot initiate and only shear fracturing may be possible. Fig. 7 shows the variation of maximum principal and maximum shear stresses along the path described in Subsection 2.3. This figure confirms that the highest maximum principal stress is tensile with a magnitude of 8.0 MPa. The variation of maximum shear stresses along the path described in Subsection 2.3 is also shown in Fig. 7. The highest maximum shear stress is approximately 12.0 MPa and occurs at θ≈-30°. Hence, if the micro-scale shear strength of the material is reached before the micro-scale tensile strength, then this is the location of initiation of a new shear crack. See also fig 27)
the fracture initiates in the middle of the fracture tip; (see page 4125- The variation of stresses around the flaw tip can be more easily understood by analyzing it along a certain path. From fracture mechanics, one knows that there is a region around the flaw tip where the stresses tend to infinity and consequently the material is plastified within this region. The path used in this study is circular with twice the radius of the flaw tip (considered semi-circular) and with the same center point, as shown in Fig. 5. The stresses along the path will be referenced to θ, the angle that a given radius makes with the flaw centerline.)
wherein the maximum principal stress comprises tensile stress and compressive stress, wherein when the fracture initiation occurs at a position with the maximum tensile stress, a tensile fracture is formed; when the fracture initiation occurs at a position with the maximum compressive stress, a compressive fracture is formed; when the tensile stress exceeds a tensile strength that the rock fracture itself can withstand, the tensile fracture is first cracked; when the compressive stress exceeds a compressive strength that the rock itself can withstand, the compressive fracture is first cracked. (see page 4125-4126- Maximum Principal Stresses represented by Element 2. These stresses were analyzed since they usually represent principal tensile stresses occurring at a certain point (they can also be compressive, if the Mohr circle is entirely located on the positive axis). Therefore, tensile cracks may initiate at the locations where these stresses are the highest. It should be noted that when both tensile and shear fractures may initiate, the fracture that will prevail is the one that first reaches the micro-scale strength of the material (tensile or shear strength for tensile or shear fractures, respectively). The maximum principal stresses are mainly tensile around the existing flaws, as shown in Fig. 6. For the inner tip of the left flaw, the highest tensile principal stress occurs in the upper face of the flaw, near the flaw tip. This is, therefore, the location of tensile crack initiation for this loading condition. The dark gray region in Fig. 6 indicates compressive maximum principal stresses, which means that both principal stresses are compressive. Under these circumstances, tensile fractures cannot initiate and only shear fracturing may be possible. Fig. 7 shows the variation of maximum principal and maximum shear stresses along the path described in Subsection 2.3. This figure confirms that the highest maximum principal stress is tensile with a magnitude of 8.0 MPa. For the loading condition in which only water pressure is applied to the existing flaws, Fig. 8 shows that there is a significant area under tensile stresses. The highest maximum principal stress occurs right ahead of the flaw tips, as Fig. 8 clearly illustrates. This is the location where a new tensile crack may initiate. It can also be noted that the maximum principal stresses in the bridge between inner flaw tips are positive, or tensile, while above and below the flaw faces the maximum principal stresses are negative, or compressive. This is in contrast with what was observed for load case 1, in which there were tensile principal stresses above and below the flaw faces, and only compressive principal stresses right ahead of the flaw tips.)
Silva explicitly does not teach obtaining rock fracture data shear modulus, and a compressive strength in one or more working areas of a reservoir containing oil or natural gas reserves, wherein the obtaining rock fracture data includes widths, densities in the reservoir; wherein the step of "according to the different horizontal stress differences, analyzing the corresponding stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip as the horizontal stress differences change, and obtaining a stress state at the fracture tip and both sides of the fracture" specifically comprises: when the horizontal stress difference is minimized the maximum principal stress on both sides of the fracture is evenly distributed; and as the horizontal stress difference increases, the maximum principal stress on the same fracture edge is unevenly stressed, and the fracture surface bends or breaks under the action of stress and strain; wherein two stress distribution states occur on the fracture surface: as the horizontal stress difference increases, the maximum principal stress decreases; or as the horizontal stress difference increases, the maximum principal stress increases accordingly; as the horizontal stress difference increases, the maximum shear stress increases, and the fracture initiates in the middle of the fracture tip to form a shear fracture, wherein the stress changes of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences are analyzed by establishing a plane change cloud map of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences according to different horizontal stress differences and the length and width of the two fractures are 0.5m and 0.02m respectively, and a perpendicular distance between two fracture tips is 0.5m; wherein, injection points and volumes of fracking fluid are selected based on the prediction to maximize fracturing efficiency. predicting initiation of rock fractures in the one or more working areas: selecting a work area for injection if conditions are favorable for rock fracture initiation; injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area.
In the related field of invention, Huang teaches obtaining rock fracture data shear modulus, and a compressive strength in one or more working areas of a reservoir containing oil or natural gas reserves, wherein the obtaining rock fracture data includes widths, densities in the reservoir; (see abstract-Hydraulic fracturing is one of the most effective ways of formation stimulation for enhancing coalbed methane (CBM) recovery. The fracture initiation and propagation during hydraulic fracturing is primary constrained by local stress field, hydraulic pressure magnitude, coal properties, and natural fractures. In this work, the fracture initiation region and propagation direction during hydraulic fracturing under various in-situ stresses were investigated both experimentally and numerically. See fig 2-3 (working areas of a reservoir containing oil or natural gas reserves) see table 1 (density) (compressive strength), (Young modulus and Poison ratio) of totally 12 coal samples. See section introduction- Moreover, a similar numerical simulation study carried out by further indicated that the hydraulic fractures initiate on the side having a weak natural fracture (i.e. the stiffness of natural fractures is lower) more efficiently grow towards it while the fracture propagation in the opposite direction is merely stopped, which manifest that the zone with lower stiffness in the reservoir is beneficial to hydraulic fracturing and improve reservoir permeability. Furthermore, numerical simulation showed the fracture radius is mainly influenced by the mechanics parameters such as elasticity modulus and Poisson's ratio. see section 3.2-For a local region in Fig. 12a, the section is parallel to the direction of σH, which shows that the original fractures scarcely developed in coal block 1#. The fracturing fluids were mainly injected into the coal block from the bottom of the simulated wellbore because of the vertical well fracturing. As shown in Fig. 12a, the yellow tracer in fracturing fluid can help to observe the original and induced fractures in coals. Many inclined fractures (IF) were created in the section of coal block 1#, the length, width and fracture density are 1–3 cm, 0.01–0.1 cm and 3/100 cm2, respectively.)
Examiner note: Elastic modulus and Poison ratio by Huang table 1 inherently defines shear modulus using well-known relationship.
wherein the step of "according to the different horizontal stress differences, (see fig 7) analyzing the corresponding stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip as the horizontal stress differences change, and obtaining a stress state at the fracture tip and both sides of the fracture" (see fig 10 -11(a)(b)(c)) specifically comprises: when the horizontal stress difference is close to 0MPa, (see fig 7 when For κ = 1.20) the maximum principal stress on both sides of the fracture is evenly distributed; (see page 72- The path varies along the semicircle with a θ ranging from −90° to 90° in anticlockwise (Fig. 6b). To conveniently extract data, the stress path is located on the symmetry plane (Fig. 4a). see fig 7, fig 10(c) and fig 15m. see page 77-, σH = σh>σv, the directions of σmin, σmax and σmid are parallel to z-axis, y-axis and x-axis near the fracture, respectively (Fig. 15m), thus, a vertical fracture is created.) and
Examiner note: Decreasing horizontal stress difference from 1.05 to 1.2 (tends to close to zero) it tends to create uniform distribution see fig 15m.
as the horizontal stress difference increases, the maximum principal stress on the same fracture edge is unevenly stressed, and the fracture surface bends or breaks under the action of stress and strain; (see fig 7 and fig 10(a) and see page 72- the fracture tip was set as hemispherical (Fig. 6a). Furthermore, due to the impact of stress and strain, a plastic zone may occur around the fracture edge.)
Examiner note: As shows in fig 7 (horizontal stress difference increases from 0.35 to 0.5) results in uneven stress distribution in fig 10(a).
wherein two stress distribution states occur on the fracture surface: as the horizontal stress difference increases, the maximum principal stress decreases; or as the horizontal stress difference increases, the maximum principal stress increases accordingly; (see fig 7 and fig 10(a)(b)(c))) as the horizontal stress difference increases, the maximum shear stress increases, (see fig 7 and fig 11(a)(b)(c)))
and the fracture initiates to form a shear fracture, (see page 73- For shear fracture initiation and followed propagation, the shear fracture will develop along the direction of θ, in which the shear stress τθ (Fig. 9a) reaches the maximum (τθmax) stress at the tip of the existing fracture)
wherein the stress changes of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences are analyzed by establishing a plane change cloud map of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences according to different horizontal stress differences. (see fig 14)
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predicting initiation of rock fractures in the one or more working areas: (see abstract- Hydraulic fracturing is one of the most effective ways of formation stimulation for enhancing coalbed methane (CBM) recovery. In this work, the fracture initiation region and propagation direction during hydraulic fracturing under various in-situ stresses were investigated both experimentally and numerically. Therefore, they can be used to predict the direction of initiation and propagation for the type of newly-created fracture during hydraulic fracturing for coalbed methane (CBM) development.)
conditions are favorable for rock fracture initiation; (see abstract- Hydraulic fracturing is one of the most effective ways of formation stimulation for enhancing coalbed methane (CBM) recovery. In this work, the fracture initiation region and propagation direction during hydraulic fracturing under various in-situ stresses were investigated both experimentally and numerically. Therefore, they can be used to predict the direction of initiation and propagation for the type of newly-created fracture during hydraulic fracturing for coalbed methane (CBM) development. The horizontal and vertical fracture are the main types when σv>σH>σh and σH>σv>σh respectively. See conclusion- σH = σv or σh = σv has a great influence on the initiate location of the compressive fracture, whereas it has no significant influence on shear fracture.
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of predicting initiation rock fractures as disclosed by Silva to include obtaining rock fracture data shear modulus, and a compressive strength in one or more working areas of a reservoir containing oil or natural gas reserves, wherein the obtaining rock fracture data includes widths, densities in the reservoir; wherein the step of "according to the different horizontal stress differences, analyzing the corresponding stress changes of maximum principal stresses and maximum shear stresses on both sides of a fracture and a fracture tip as the horizontal stress differences change, and obtaining a stress state at the fracture tip and both sides of the fracture" specifically comprises: when the horizontal stress difference is minimized the maximum principal stress on both sides of the fracture is evenly distributed; and as the horizontal stress difference increases, the maximum principal stress on the same fracture edge is unevenly stressed, and the fracture surface bends or breaks under the action of stress and strain; wherein two stress distribution states occur on the fracture surface: as the horizontal stress difference increases, the maximum principal stress decreases; or as the horizontal stress difference increases, the maximum principal stress increases accordingly; as the horizontal stress difference increases, the maximum shear stress increases, and the fracture initiates in the middle of the fracture tip to form a shear fracture, wherein the stress changes of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences are analyzed by establishing a plane change cloud map of the maximum principal stresses on both sides of the fracture and the maximum shear stress at the fracture tip with the change of the horizontal stress differences according to different horizontal stress differences and predicting initiation of rock fractures in the one or more working areas; conditions are favorable for rock fracture initiation as taught by Huang in the system of Silva in order to predict the fracture initiation region and propagation direction under various in-situ stresses (or horizontal stress difference) for the type of newly-created fracture during hydraulic fracturing for coalbed methane (CBM) development. (See Abstract, Huang)
The combination of Silva and Huang does not teach the length and width of the two fractures are 0.5m and 0.02m respectively, and a perpendicular distance between two fracture tips is 0.5m; wherein, injection points and volumes of fracking fluid are selected based on the prediction to maximize fracturing efficiency. selecting a work area for injection if conditions are favorable for rock fracture initiation; injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area.
In the related field of invention, Soliman teaches the length and width of the two fractures are 0.5m and 0.02m respectively, and a perpendicular distance between two fracture tips is 0.5m; (see para 002- Conventional fracture designs focus on the creation of a fracture of desirable length, height and width. It is also desirable to increase fluid efficiency to reduce the amount of fluid to be used and to minimize damage to the proppant pack in the fracture. Such considerations typically lead to a fracture design using a reasonably high pump rate and as low a viscosity of the fracturing fluid as possible given the viscosity requirement for the desired fracture size. see para 46-FIGS. 2a-2d are plots of the change in stress anisotropy in the area between two fractures. Two transverse fractures are placed in various distances to illustrate the effect of spacing between fractures on the change in stress anisotropy. See fig 11-12 (fracture length ranges from 0 to 800ft) and (fracture width ranges from 0 to 1inch))
wherein, injection points and volumes of fracking fluid are selected based on the prediction to maximize fracturing efficiency; (see para 001-The present invention relates generally to compositions and methods for hydraulic fracturing of an earth formation and in particular, to compositions and methods for hydraulic fracturing by optimizing the placement of fractures along the deviated wellbores to enhance far field complexity and maximizing the stimulated reservoir volume. see para 0008-0014-introducing a series of fractures in the deviated wellbore. By understanding reservoir rock mechanics and those parameters that have a major impact on the performance of fracture treatments, more reliable decisions in fracturing design and optimization can be made. The present invention provides an analytical method that predicts the changes in stress anisotropy in the neighborhood of the fractures of different designs in an elastic-static medium The third fracture may be created in the other well in a distance between the first two fractures. See para 0045-The narrower fracture width dictates the use of a lower proppant concentration and size. The proppant concentration pumped will depend on the type of treatment; whether it is slick water or hybrid frac. See para 0034-0035- The present invention places fractures at different spacing. In conventional hydraulic fracturing, fractures are placed along the wellbore with consistent spacing. Therefore, the net pressure required for the creation of each fracture is a function of cumulative stresses induced by all previously created fractures.)
selecting a work area for injection if conditions are favorable for rock fracture initiation; (see para 0001- The present invention relates generally to compositions and methods for hydraulic fracturing of an earth formation and in particular, to compositions and methods for hydraulic fracturing by optimizing the placement of fractures along the deviated wellbores to enhance far field complexity and maximizing the stimulated reservoir volume. see para 0007-This invention discloses a method used to design new fracturing schemes based on mechanical properties of the subterranean formation. The ultimate objective of the disclosed invention is to enhance production from unconventional reservoirs by optimizing the fracture placement in hydraulic fracturing designs. see para 56-58- Stress reversal occurs if the change in stress anisotropy exceeds the original value. Any fracture initiated in the stress reversal region will propagate along the axis of a wellbore. The present invention discloses a method to introduce a fracture at a greater distance from the previous fracture where minimum (optimum) stress exists so that the net pressure can overcome the stress anisotropy, thereby creating a long fracture.)
injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area. (See para 0001- hydraulic fracturing of an earth formation. See para 0009-0010-The present invention provides a method of hydraulically fracturing a well penetrating an subterranean formation The one or more complex fractures may connect to one or more pre-existing network of natural fractures to form the complex fracture network and the series of as fractures reduces a principal stress, a shear stress or both. The series of as fractures are generated as a function of a fluid flow and a stress interference. See para 35- Therefore, the net pressure required for the creation of each fracture is a function of cumulative stresses induced by all previously created fractures.)
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the method of predicting initiation rock fractures as disclosed by Silva to include the length and width of the two fractures are 0.5m and 0.02m respectively, and a perpendicular distance between two fracture tips is 0.5m; wherein, injection points and volumes of fracking fluid are selected based on the prediction to maximize fracturing efficiency. selecting a work area for injection if conditions are favorable for rock fracture initiation; injecting fracturing fluid with a high viscosity into the selected working area of the reservoir, thus obtaining hydraulic fracturing of the working area as taught by Soliman in the system of Silva and Huang for optimizing the spacing of fractures along a wellbore to form a complex network of hydraulically connected fractures, thus enhancing production from reservoirs by optimizing the fracture placement in hydraulic fracturing designs. (See Abstract and para 007, Soliman)
Conclusion
12. The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
Soliman et al. US 20140048270 A1
Discussing a method to hydraulic fracturing that reduces stress contrast during fracture propagation while enhancing far field complexity and maximizing the stimulated reservoir volume.
Da Silva, B. Gonçalves, and H. H. Einstein. "Study of stress and strain fields around a flaw tip in rock." ARMA US Rock Mechanics/Geomechanics Symposium. ARMA, 2012.
Discussing a study of crack initiation and propagation\ for the understanding of rock mass behavior, which affects many rock engineering problems. Here, a numerical study is presented, in which the stress and strain fields around a flaw tip were analyzed using the finite element code, ABAQUS, to better understand the processes involved in crack initiation and propagation.
13. Claim 1 is rejected.
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/PURSOTTAM GIRI/
Examiner, Art Unit 2186
/RENEE D CHAVEZ/Supervisory Patent Examiner, Art Unit 2186