Integration Research On The3D Geological Modeling And Reservoir Simulation Of BZ A Oilfield

Bo zhong A Oilfield is located in the south Bohai and the block is located in the west pitch side of Bonan Uplift. It adjoins Bozhong Uplift on the north and nexts to Huanghekou Sag on the south. The structure presents draping semi anticline pattern which is controlled by fault. There are two rich hydrocarbon generation depression next to Bozhong A Oilfield and the faulting and oil-gas migration exist meanwhile, which make the structure have superior geological conditions. Moreover, Bozhong A Oilfield has some characteristic, such as complicated reservoir type, many oil-bearing strata, complex oil-water relationship, bad reservoir connectivity. Complex geologic feature brings lots of difficult to calculate oil and gas reserves and formulate whole development project. Therefore, describing reservoir and inner structure subtly, revealing the law of oil and gas distribution, constructing3D quantitate distribution model of reservoir, reappearing geologic structure and reservoir characteristic truly and visually, describing non-homogeneity of reservoir parameter, designing numerical simulation net system, transforming the elaborate geological model into numerical simulation static model, they have important significance to optimize and adjust development program of Bohai A Oilfield.Adopting multidisciplinary integration principle, according to geological theory and3D geological modeling theory, utilizing seismic, drilling, logging, testing and analytical test data, based on research of geology, logging data comprehensive explanation, reservoir prediction, advanced3D visual geology modeling software, which is called Petrel TM, is used to construct elaborate certainty and randomness3D geology model. In some certain condition, probable change process is confirmed, then according to the specific purpose, the most reasonable geological model is selected and obtained. On the basis of selected model, numerical simulation research can be carried out, output predict target is updated, formulating the development strategy can be guided, the whole and deep study can be carried out. The main research results and cognition follows:1) Meandering stream deposit, braided river deposit, delta deposit and alluvial fan deposit develop in research area. The type of sand-mudstone are varied. Point bar, natural levee, flood plain of meandering stream environment develop in the bottom of Minghuazhen Strata; river island, overflow facies, flood plain of braided river deposit environment develop in Guantao Strata; distributary channel, estuary dam of delta deposit environment develop in Dongying Strata. 2) By ranking some equal probability model, the uncertain factor of3D geological model is evaluated and the model is optimized. The optimized reservoir stratum should be distributed reasonably. A set of model, in which reserves fitting and geological reserve are closely, should be provided to reservoir numerical part.3) The reservoir type is very complex and there are many oil-bearing series in the reservoir, but the single pay sand is very thin. Oiliness well section is long and it is up to1000m and pressure difference is big; moreover, the reserve of Nmi, Ngo1, Ngo2is relative small, many of which are isolate pay sand or oil and gas reservoir. The value of exploitation is not high in initial stage. Therefore, the rational development strategy is confirmed, producing Ngi, NgⅡ, NgⅢ, NgⅣ, Ed1and Ed2first; Nml, Ngo1, Ngo2are not perforated early stage in principle, when going into productivity decreasing stage, corresponding strata should be perforated to produce.4) The calculate result based on theory formula and numerical simulation research indicate that the rational flow pressure is10MPa, critical flow pressure is6MPa, rational productive pressure should be controlled2MPa below and the biggest value can’t be pass8MPa.5) The connectivity of inner layer and interlayer is bad. The relationship between oil and water is complex. The water energy of this oilfield is abundant and formation pressure decreases slowly. The comparison result between water flooding and natural depletion shows that the effect of injecting water is not well and its recovery is closely to the recovery of natural depletion. Therefore, natural depletion should be adopted.6) The uncertain factors of influencing development effect are analyzed and assessed, which are net size of numerical simulation, the whole volume of rock, permeability, longitudinal connectivity, coefficient of compressibility, irreducible water saturation, the height of oil-water belt zone, skin factor. According to the assessed results we can estimate the influence of those factors to development effect.7) Using established geological model, seven productive strategies are designed. The simulation predict result indicates that the producing effect of increasing volume is better than not increasing volume, interlayer interference phenomenon decreases in some extent when adopting turning on sliding sleeve successively and the time of producing stably is extended. The screened producing strategy is that rate of oil production is about3%in early stage and recovery percent of reserves is up to11.7%after producing18years.8) The numerical simulation result shows that recovery percent of reserves is low. There are three reasons as follows:(1) there are many isolated reservoir, the relationship between oil and water is complex, the degree of producing reserves is low;(2) the distance to boundary water and bottom water is small and water invades quickly.(3) there are many oil-bearing series in the reservoir, but the single pay sand is very thin. Oiliness well section is long. The difference of pressure is big. Fluid channeling and interlayer interference phenomenon are serious.By establishing high-precision3D geological model of Bozhong A Oilfield, including3D geological structure model, certainty and randomness sedimentary model, rock physics model controlled by phased, inaccurate3D geological model, in some certain condition, probable change process is confirmed, then according to the specific purpose, the most reasonable geological model is selected and obtained.On the basis of selected model, numerical simulation research can be carried out, output predict target is updated, formulating the development strategy can be guided and it can provide technical support to optimization and adjustment of development strategy of Bozhong A Oilfield.