Prosecution Insights
Last updated: April 19, 2026
Application No. 18/705,601

METHOD FOR IMPROVING GAS STORAGE CAPACITY OF NATURAL GAS HYDRATE BASED ON CRYSTAL REGULATION AND CONTROL PRINCIPLE

Non-Final OA §103§112
Filed
Apr 29, 2024
Examiner
NGUYEN, TAM M
Art Unit
1771
Tech Center
1700 — Chemical & Materials Engineering
Assignee
Guangzhou Institute Of Energy Conversion Chinese Academy Of Sciences
OA Round
1 (Non-Final)
78%
Grant Probability
Favorable
1-2
OA Rounds
2y 9m
To Grant
88%
With Interview

Examiner Intelligence

Grants 78% — above average
78%
Career Allow Rate
746 granted / 963 resolved
+12.5% vs TC avg
Moderate +11% lift
Without
With
+10.9%
Interview Lift
resolved cases with interview
Typical timeline
2y 9m
Avg Prosecution
68 currently pending
Career history
1031
Total Applications
across all art units

Statute-Specific Performance

§101
0.1%
-39.9% vs TC avg
§103
51.2%
+11.2% vs TC avg
§102
16.7%
-23.3% vs TC avg
§112
18.7%
-21.3% vs TC avg
Black line = Tech Center average estimate • Based on career data from 963 resolved cases

Office Action

§103 §112
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 . 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 1-6 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. In line 4 of claim 1, the phrase “unstable II-type pure methane hydrate” is indefinite because the claim does not specify any objective structural, compositional, thermodynamic, or temporal criterion by which the instability of the structure II methane hydrate is determined. The claim does not define whether “unstable” refers to metastability, kinetic instability, thermodynamic instability, a measurable lifetime, a dissociation rate, or a phase equilibrium condition, nor does it provide any test or parameter by which one of ordinary skill in the art could ascertain whether a given hydrate falls within the scope of this term. Additionally, in line 5 of claim 1, the phrase “quickly transforming” is a relative and subjective term that lacks an objective boundary. The claim does not specify any time interval, rate of transformation, or measurable criterion that would distinguish a “quick” transformation from a non-quick transformation. As a result, the scope of the claim cannot be determined with reasonable certainty. Claim Rejections - 35 USC § 103 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 (i.e., changing from AIA to pre-AIA ) 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. 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. 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. Claims 3-5 are rejected under 35 U.S.C. 103 as being unpatentable over Uchida et al. “Two-step formation of methane–propane mixed gas hydrates in a batch-type reactor,” AIChE Journal, Vol. 50, pp. 518–523, 2004. Uchida discloses a method for forming gas hydrates from methane and propane in a batch-type reactor under controlled temperature and pressure conditions. Uchida further discloses that a structure II hydrate containing methane forms initially and subsequently transforms into a structure I methane hydrate, as confirmed by X-ray diffraction and Raman spectroscopy (see Uchida, Abstract; Results and Discussion; Figs. 2–5). The process is conducted at a temperature of approximately 274.0 ± 0.1 K and pressures of about 5–7 MPa. The initially formed structure II hydrate is inherently unstable, as evidenced by its inevitable transformation into a structure I methane hydrate under continued operation at substantially the same conditions. Formation of such unstable structure II methane hydrate therefore necessarily and inevitably occurs when practicing Uchida even though such intermediate is not expressly labeled as such. Recognition of this inherent feature by Uchida et al. is not required. Regarding claims 1 and 5, Uchida does not teach the temperature as claimed. However, temperature is a results-effective variable in hydrate formation processes, and Uchida teaches hydrate formation behavior as a function of temperature and pressure. It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Uchida by adjusting the operating temperature slightly upward from approximately 274 K to within the claimed range while maintaining pressures within the hydrate region to obtain the same hydrate transformation behavior. With respect to claim 2, Uchida expressly discloses the use of propane as the hydrate-forming additive. Regarding claim 3, Uchida et al. do not explicitly disclose a numerical volume ratio of thermodynamic additive to water. However, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to have modified the process of Uchida by selecting a particular additive-to-water volume ratio within the claimed range of (15–24):(76–85) would have been an obvious matter of routine optimization of a result-effective variable in hydrate formation processes. With respect to claim 6, Uchida expressly discloses that gas hydrates are applicable to natural gas storage and transportation. Claim 4 is rejected under 35 U.S.C. 103 as being unpatentable over Uchida as applied to claim 1 above, and further in view of Baek et al. “Enhanced methane hydrate formation with cyclopentane hydrate seeds” (Applied Energy 202, 32–41, 2017). Uchida does not teach the use of cyclopentane. It would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to substitute cyclopentane for propane in the method of Uchida because both compounds are well-known structure-II hydrate formers that stabilize large hydrate cages and are used as thermodynamic additives to control hydrate crystal structure. Baek teaches that cyclopentane forms structure-II hydrates and promotes methane hydrate formation via crystal structure regulation. A person of ordinary skill in the art would have reasonably expected that substituting cyclopentane for propane would predictably result in structure-II hydrate formation and subsequent methane hydrate formation under comparable temperature and pressure conditions, while offering practical advantages in handling and process control. Accordingly, the substitution represents no more than a predictable variation. Conclusion Any inquiry concerning this communication or earlier communications from the examiner should be directed to TAM M NGUYEN whose telephone number is (571)272-1452. The examiner can normally be reached Mon - Frid. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Prem C Singh can be reached at 571-273-6381. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /TAM M NGUYEN/Primary Examiner, Art Unit 1771
Read full office action

Prosecution Timeline

Apr 29, 2024
Application Filed
Jan 20, 2026
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

1-2
Expected OA Rounds
78%
Grant Probability
88%
With Interview (+10.9%)
2y 9m
Median Time to Grant
Low
PTA Risk
Based on 963 resolved cases by this examiner. Grant probability derived from career allow rate.

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