# Borehole Condition and Limit Pressure Differential Analysis in Carbonate Reservoirs
## 7 Conclusions  
* The analysis of stress distributions in deep carbonate reservoirs during open-hole testing has been conducted, employing principles of elasticity theory. It revealed a dichotomy in wellbore angles influenced by stress anisotropy: those oriented toward lesser differential stresses, deemed safe, and those aligned with higher differentials, posing a risk;
* Laboratory rock mechanics assays were instrumental in delineating the failure attributes and mechanical characteristics of carbonate reservoirs. Deep carbonate core specimens displayed brittle fracture under reduced confining pressures, transitioning to marked plastic behavior en route to peak strength at elevated pressures, and retained considerable residual strength post-failure;
* Incorporating the peak, yield, and residual strength profiles of carbonate rocks, the zones surrounding the wellbore were delineated into elastic, plastic, and residual failure regions, guided by the Mohr-Coulomb criterion. The transition of the adjacent rocks into the residual failure regime signifies impending wellbore collapse and block detachment;
* To establish the analysis method for the limit testing pressure differential, we used criteria such as the ratio of the total volume of the plastic region to the wellbore volume not exceeding 20%, the ratio of the volume of the failure region to the wellbore volume not exceeding 10%, and the maximum failure angle of the wellbore of less than 90\({}^{\circ}\). Implemented in ultra-deep carbonate reservoir field settings, this approach yielded congruent and satisfactory outcomes, affirming its alignment with practical engineering realities.  
Methodology, L.W. and Q.T.; validation, L.W. and P.S.; formal analysis, Q.T. and P.S.; investigation, Q.T.; data curation, L.W., P.S., and K.L.; writing--original draft, Q.T.; writing--review and editing, K.L. and N.H.; visualization, Q.T. and N.H.; project administration, L.W. and P.S.; funding acquisition, L.W. All authors have read and agreed to the published version of the manuscript.  
This research was funded by Research on Key Technologies for Drilling and Completing of Ultra-deep Wells in the Shunbei Block (key project of Sinopec Northwest Oilfield Branch, No. 34400007-21-ZC0607-0199) and Research and Engineering Application of Key Technologies for Completion and Reconstruction of 10000 m Deep Wells in Tarim Basin (Project of Sinopec Ministry of Science and Technology, No. P24157).  
Not applicable.  
Data Availability Statement: Data are contained within this article.  
Authors [PERSON] and [PERSON] were employed by the company Northwest Oil-field Branch of China Petrochemical Corporation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare that this study received funding from China Petrochemical Corporation. The funder was not involved in the study design, collection, analysis, interpretation of data, the writing of this article or the decision to submit it for publication.