Characteristics of in-situ stress field and its impact on hydraulic fractures in Qiongzhusi Formation shale,Jingyan area,southern Sichuan
MA Shunting
LI Ruixue
SU Hang
WANG Xiaozhen
XIONG Liang
DENG Hucheng
DU Yifei
HE Jianhua
LI Kesai
XING Zimeng
Abstract：The discovery of oil and gas in the Lower Cambrian Qiongzhusi Formation shale of the Sichuan Basin has opened up a new frontier for shale gas reserve growth.To delineate the current in-situ stress characteristics of the Qiongzhusi Formation shale in the Jingyan area,southern Sich-uan,and their impact on hydraulic fractures,this study conducted a detailed interpretation of in-situ stress orientation and magnitude along well profiles using integrated multi-source data.A refined geological structure model and a heterogeneous geomechanical model were constructed.Building upon the constraints provided by single-well interpretations,a 3D simulation was performed to pre-dict the distribution of the current in-situ stress field.This clarified the distribution characteristics of in-situ stress in the study area and its influencing factors.Subsequently,horizontal well fracturing simulations were conducted to analyze the impact of current in-situ stress on fracture propagation.The main research findings are as follows.The magnitude of in-situ stress and the horizontal stress difference are primarily controlled by burial depth.Vertically,stress locally increases within the black shale-bearing layers 1,5,and 9 due to lithological influence.Planarly,the northwestern and southeastern parts of the study area exhibit higher values,while the middle part shows lower val-ues.In-situ stress magnitude and horizontal stress difference decrease near faults.NE-trending faults have a greater influence on stress magnitude compared to NW-trending faults.The larger the fault scale,the more pronounced the impact.Structural deformation has a relatively weak influence.For the target layer 7,the maximum horizontal principal stress,minimum horizontal principal stress,and vertical principal stress mainly range between 75-95,60-80,and 65-85 MPa,respec-tively.The horizontal stress difference primarily ranges between 11-16 MPa.The orientation of the maximum horizontal principal stress in the study area is predominantly concentrated between N75°-90°E.Influenced by structural deformation,the maximum horizontal principal stress orienta-tion slightly rotates counterclockwise in the southwestern plunging end of the Weiyuan Anticline.In the Tieshan Anticline area and the central pinch zone,the maximum horizontal principal stress ori-entation rotates clockwise by approximately 5°—10° due to fault influence.NE-trending faults have a greater impact on in-situ stress orientation than NW-trending faults.An increase in the minimum horizontal principal stress leads to a decrease in fracture length,width,height,and stimulated reser-voir volume.An increase in the horizontal stress difference results in an increase in fracture length but a decrease in fracture width,height,and stimulated reservoir volume.Better fracturing effec-tiveness is achieved when the well trajectory has a larger angle with the maximum horizontal princi-pal stress direction,and when the minimum horizontal principal stress and horizontal stress differ-ence are relatively small.The research results can provide a reference for the study of in-situ stress in shale reservoirs and the efficient exploration and development of shale gas.
Keywords：southern SichuanQiongzhusi Formationshalecurrent in-situ stress fieldfracturing simulation
Publication Date：2026-01-30
Online Publishing Date：2026-01-28(First online date of this platform, not the publication date of the document)
Pages：19( 213-231 )