Study On Injection-production Scheme Based On Fault Stability Evaluation Of Z Oilfield

Z oil field is located in the Chengning tectonic zone with very developed faults.After three development stages,it has now entered the high water-content development stage,where the water-content rate increases year by year,and the final recovery rate decreases year by year,and the reservoir mismatch is gradually exposed.Long-term high-intensity water injection development has changed the stress field in the subsurface,which may lead to changes in the stability and closure of the fault,thus affecting the normal safe production of the platform.In this thesis,based on the positive correlation between the mud content of the fault zone and the differential pressure of fault closure in Z oilfield,combined with reservoir engineering methods,the faults are classified into four types: lateral leakage,weak closure,medium closure and strong closure;combined with the development dynamic data of Z oilfield,a numerical model of the fault is established to characterize the conduction factor;through historical fitting,the causes of remaining oil formation are studied to make a basis for the optimization of the later injection and extraction scheme;an actual The critical value of fault disturbance in Z field is 28.97 MPa,and the fault can remain stable and the oil production rate increases when the injection and production ratio is 1.1 and the injection rate is 0.14PV/a.In the actual field development process,it is necessary to consider the stability of the fault to formulate a reasonable injection pressure for water injection wells,and consider the different activation pressure and cover rupture pressure of each fault.In the actual field development process,it is necessary to consider the stability of the faults to develop a reasonable injection pressure,taking into account the activation pressure of each fault system and the rupture pressure of the cover layer,and taking the lowest value of both for each layer.Compared with the base scheme,the formation pressure increased by 3.63 MPa after the implementation of the generalized water injection scheme,resulting in an increase of 1.722 million tons of oil;because the Z oilfield is an offshore oilfield,in order to achieve the purpose of pursuing shortterm benefits,this thesis selects injection wells with prominent inter-stratum permeability variation coefficient and inter-stratum conflicts from the generalized water injection wells for fine distribution,taking into account the different distribution of remaining oil in each block and combining the layer segmentation and liquid volume splitting methods.Compared with the basic plan,the formation pressure rises by 3.88 MPa and 1.8483 million tons of oil is added after the implementation of the layered injection plan;compared with the generalized water injection,the formation pressure rises by 0.26 MPa and 126,000 tons of oil is added.