Geomechanical Analysis for Deep Shale Gas Exploration Wells in the NDNR Blocks, Sichuan Basin, Southwest China

Majia Zheng, Hongming Tang, Hu Li, Jian Zheng and Cui Jing
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Majia Zheng: School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Hongming Tang: School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Hu Li: School of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, China
Jian Zheng: PetroChina Southwest Oil and Gasfield Company, Chengdu 610000, China
Cui Jing: PetroChina Southwest Oil and Gasfield Company, Chengdu 610000, China

Energies, 2020, vol. 13, issue 5, 1-24

Abstract: The abundant reserve of shale gas in Sichuan Basin has become a significant natural gas component in China. To achieve efficient development of shale gas, it is necessary to analyze the stress state, pore pressure, and reservoir mechanical properties such that an accurate geomechanical model can be established. In this paper, Six wells of Neijiang-Dazu and North Rongchang (NDNR) Block were thoroughly investigated to establish the geomechanical model for the study area. The well log analysis was performed to derive the in-situ stresses and pore pressure while the stress polygon was applied to constrain the value of the maximum horizontal principal stress. Image and caliper data, mini-frac test and laboratory rock mechanics test results were used to calibrate the geomechanical model. The model was further validated by comparing the model prediction against the actual wellbore failure observed in the field. It was found that it is associated with the strike-slip (SS) stress regime; the orientation of S Hmax was inferred to be 106–130° N. The pore pressure appears to be approximately hydrostatic from the surface to 1000 m true vertical depth (TVD), but then becomes over-pressured from the Xujiahe formation. The geomechanical model can provide guidance for the subsequent drilling and completion in this area and be used to effectively avoid complex drilling events such as collapse, kick, and lost circulation (mud losses) along the entire well. Also, the in-situ stress and pore pressure database can be used to analyze wellbore stability issues as well as help design hydraulic fracturing operations.

Keywords: shale gas; geomechanical model; stress state; pore pressure; mechanical properties; NDNR block; Sichuan Basin (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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