Research On Ground Stress Direction Characteristics Of Fuyang Oillayer In Xing71 Wellblock

Xing71 wellblock is located in Xingshugang oil field which is in Daqing Placanticline on central depression in Songliao Basin. Fuyang oil layer lies in cretaceous Quan3 and Quan4 member of Mesozoic. Based on the predecessors’ research results, hydraulic fracturing data,drilling and logging data of the study area, guided by theories of mathematics, mechanics,geology,etc., this paper systematically carry out size and direction of ground stress, ground stress field numerical simulation, stress distribution influence factors analysis and fracture distribution prediction.By hydraulic fracturing data, logging data and the finite element method(fem) numerical simulation research, we know that, the maximum horizontal ground stress of 71 wellblock FⅠ layer is between 32.20 MPa and 38.73 MPa, minimum horizontal principal stress is between 22.76 MPa and 30.28 MPa, the maximum horizontal ground stress of 71 wellblock FⅡ layer is between 30.15 MPa and 36.52 MPa, minimum horizontal principal stress is between 25.34 MPa and 29.6 7MPa. The maximum horizontal principal stress direction of Xing 71 wellblock isroughly east-west, the maximum horizontal stress orientation of FⅠ1~FⅡ5 layers is nearly east-west, FⅠgroup is between NE45°~NE110°, FⅡgroup is between NE55°~NE102.4°. By changing the regional stratigraphic petrophysical parameter of Xing71 wellblock, we simulate and validate the ground stress distribution change, mainly considers the lithological changes and fault properties which impact the regional stress field.Wells core fracture statistics of Xing71 wellblock and the surrounding shows that fracture attitude of Xing71 wellblock monitoring well fracturing is vertical, nearly east-west direction, roughly NE 80.9° to NE 102.4°, left slit is 29.1~44.4m, right slit is 30~58.6m.Fracture cutting through the study area of T2 structural stage is mainly for the NNW direction,maximum slip is 114 m, most are less than 100 m, average aligement of fault is 148°. Overall law of fracture is that density of upper wall is bigger than the bottom wall, while, density of the position which fracture aligement changes in, fracture intersecting position and the ends of fracture is larger.Situ stress magnitude and direction determines the construction pressure and crack initiation, azimuth, extending direction and extend trajectory of fracture. Therefore, to find out the stress distribution and fracture characteristics has significance for submitting economic disposable proved reserves, but also can provide protection for the further development scheme of injection patterns and improvement of reserves producing economic benefit.