The Present Ground Stress Field Characteristics And Evaluation--Take Jurassic In Mid Of West-Sichuan-Depression For Example

The paper mainly analyzes and evaluates the distribution characteristics and laws about the present ground stess field at Jurassic in mid of West-Sichuan-Dep-ression by means of stess calculation method including Hydrofr -acturing method,Rock Acoustic Emission method and Logging method combined with stress field finite element simulation.On base of a quantity of original data and calculated data,after systemi -cly analyzing many geologic factors such as rock mechanical property.drilli-ng-hole depth,formation and tectonic shape,location and hypsography etc.whi -ch influnce the present ground stress field distributing characteristics and laws,a series of theoretical viewpoints and research fruition are concluded.After analyzing relation between stress characteristics and hydrofracturi-ng fracture, then a conclusion comes into being that the present ground stress characteristics mainly influnce fractured model and parameters of fracture.There exist three diverse stress state resulting in three different fractu -red models in destination area.Comibined with former research fruitions, a identifying model is found by using hydrofracturing information so as to dist -inguish fractureextended states.And after applied this identifying model to all hydrofractured wells,the present ground stress states in penglaizhen and shaximiao formation are mastered.By statistic,generation and deducing,the mutual ralation appear between deviation stress and fractured pressure,fracture extended length .increased production quantity of natural gas.Considering numerical value of principal stress and deviation stress,stress state characteristics,tectonic location,stres s difference between destination layer and segregation layer and the criterion which classify the present ground stress profile,a standard about how to select a layer for executing hydrofracturing is established including some related parameters in paper.Finally through anlysing fracture direction and length,indispensablly synthetical considering the present ground stress characteristics state, the par -ameters about direction and distance between wells are determined at Jura -ssic in mid of West-Sichuan-Depression in paper.