Quantitative Research On Hydraulic Fracturing Conditions Of Fault Rocks In Qinhuangdao 33-1S Oil Field

In the process of water injection development of offshore oil field,due to the effect of higher residual water injection pressure,hydro fracturing will occur on fault rock in the fault type reservoir.Consequently oil and gas will escape to the bottom of the sea through fracture plane causing the accidence of oil spill.In order to prevent such accidents,this paper chooses the Qinhuangdao 33-1S oil field as the target section,with the help of the National Science and Technology Major Project,the National Basic Research Program of China(973 Program)and the Heilongjiang Province Graduate Innovation Fund,from the perspective of the evolution characteristics of faults development and anatomy of the reservoir,this essay sets out the risk fault which are needed hydraulic fracturing risk evaluation,on the basis of geological analysis and experimental test,the occurrence mechanism and influence factors of fault rock hydraulic fracturing has been clear.By establishing hydraulic fracturing occur methods to quantitatively predict conditions and seeing the reasonable water injection development oilfield safety,this paper carries out risk assessment on hydraulic fracturing of fault rock.Following are the main achievements and understanding.1.The faults developing in the Qinhuangdao 33-1S oil field is the late new fracture.On the influence of the late right-lateral strike-slip stress field the research area in east side of Tanlu fault zone,the faults give priority to nearly NEE,and most of the reservoir boundary faults broke up to the bottom of the sea which is exiting the risk of oil spill.All is need for fault rock hydraulic fracturing oil escape risk evaluation.2.By means of combining the geological analysis and laboratory test,this paper establishes the function relationship of hydraulic tensile fault rock burst pressure and rock properties and conducts hydraulic shear fracture pressure prediction of fault rocks in target fracture in the Qinhuangdao 33-1S oil field based on the theory of hydraulic fracturing of rock oil engineering research.The results show that,when risk fault hydraulic tensile rupture occurs,the critical maximum residual water injection pressure is 20.4?23.1MPa,an average of 21.4 MPa?3.Through the three-dimensional stress analysis of fault plane and the method of regional stress field analysis,based on the the study of the theory of the fault sliding friction in the field of natural earthquake prediction,the hydraulic shear sliding rupture occurred fault rock model is established,and by conducting target Qinhuangdao 33-1S oil field fault rock hydraulic shear fracture pressure prediction.It turned out that when the fault rock friction coefficient is 0.4,the critical maximum residual water injection pressure of fault rock shear rupture is range of 11.9?11.9 MPa,an average of 21.1 MPa;when the fault rock friction coefficient is 0.5,the critical maximum residual water injection pressure of Fault rock shear rupture is range of 15.3-63.2 MPa,an average of 25.4 MPa.4.Based on the above research,this paper carries out risk assessment on hydraulic fracturing of fault rock.Results show that as the water injection pressure increases,when the fault rock friction coefficient is 0.4,the risk fault mainly is hydraulic shear rupture;when the fault rock friction coefficient is 0.5,the risk fault is given priority to hydraulic tensile rupture.