The Research And Application Of Crustal Stress In Wuliyasitai 53 Block Oilfield

Huabei Oilfield has a large number of low permeability and poor quality reservoirs.However,the earlier stimulation effect is unsatisfactory for the lack of the stress field distribution data.This paper adduces Wuliyasitai NO.53 block oilfield as the representative.Based on the rock mechanics test and the analysis of actual logging data by Res Form,the three-dimensional finite-element method is used to calculate the crustal stress field,which is performed by ABAQUS(software for finite-element).Wuliyasitai NO.53 block oilfield is composed of glutenite and conglomerate.The reservoirs have a series of characteristics: low porosity,low permeability,heterogeneity,and strong water sensitivity,moderate alkali sensitivity,etc.But it is still worth stimulation for its large reserves and ideal fracturing evaluation results.In this paper,the formula of transform dynamic and static rock mechanics parameters is established for the block oilfield.It significantly decreases the cost of acquiring rock mechanics parameters.According to different continuous well stress profiles,the evaluation results of earlier stimulation effect are more accurate.This paper applies three-dimensional finite-element numerical simulation to calculate crustal stress field,and acquires a relatively accurate stress field.Then,the paper estimates the horizontal differential stress and analyses the change of propagating direction around the fractures.The accurate stress field obtained from this paper is an important theoretical foundation of future stimulation design.Based on adequate data of stress field,this paper proposes an innovative method to analyze the feasibility of volume fracturing in vertical well.It analyzes from four aspects: reservoir lithology,rock mechanics,stress difference of reservoir and restraining barrier and the difference between maximum horizontal stress and minimum horizontal stress.Finally,a comprehensive evaluation is given.In June 2015,the first fracturing volume vertical well in Wuliyasitai NO.53 block oilfield acquires excellent stimulation effect,and it significantly verifies the feasibility of vertical well fracturing volume.