| Carbonate reservoirs play a very important role in the discovered oil and gas reservoirs in the world.The heterogeneity of carbonate reservoir is strong and the productivity of single well is quite different,which increases the difficulty of development.Carbonate reservoir has become a hot spot at home and abroad,especially the fracture modeling technology is difficult.Based on core,logging and seismic data,this paper studies the fracture characterization parameters,structural fracture control factors and so on in Jurassic Kalov-Oxford carbonate reservoir in Bie-pi gas field.And set up the fracture density model,discrete fracture network model and calculate the reserves of the study area,which provides the geological basis for the preparation of gas field development plan,the deployment and implementation of well location and the stable production of gas reservoir.The Bie-Pi gas field is located in the middle of the old three-dimensional block on the right bank of the Amu River in Turkmenistan.The fault is relatively developed in the middle of the Sandickley uplift in the Char-Zhu stage,which belongs to the Amhe River anticline.Both strike north-west(or near east-west direction)strike-slip fault;There are also trending north to the east of the main thrust fault.The Neogene,Paleogene,Cretaceous and Jurassic strata have been drilled from top to bottom in the Bei-Pei gas field.The main targets are the subreef(XVhp),massive limestone(XVal)and massive limestone(XVa2)of the Karov-Oxford stage of the Upper Jurassic.The Kalov-Oxford carbonate rocks on the right bank of Amu River are mainly limestone containing a small amount of dolomite and gypsum and even a thin layer of mudstone and silty mudstone.The sedimentary microfacies in the main part of the gas field are beach facies and hilly-beach complex of the upper slope of the platform margin.The reservoir types are mainly pore type and fracture-pore type.The porosity of core in Bie-Pi area is between 2%and 12%,the average porosity is 7%,the effective permeability of well testing is 1.03mD,the reservoir of Bei-Pei gas field belongs to low porosity and low permeability reservoir.The main fractures in Bei-Pi gas field are structural fractures:structural fractures associated with faults and structural fractures associated with folds.The fractures are divided into four groups:F1,F2,F3 and F4.The average length of large-scale fractures(i.e.faults)is 3621m.The strike is mainly north-west and NE-trending,with an average dip of 20°;The average length of medium-small scale fractures is 25 m,the distribution is relatively scattered,and the dip is 0°-30°;The average length of microfissures is 0.93m,which is mainly trending north-west and north-east,with an average dip of 36°.The fracture opening is less than 1mm?the filling degree is low,and the unfilled is the main one.In this study,the fracture density is calculated directly from the fracture data at the wellbore,and then the fracture density distribution model is obtained by combining with the relevant constraints(for example,lithologic spatial distribution models,fault distances,curvature bodies,ant bodies,well-lost data,and productivity data).Due to the multi-scale characteristics and strong heterogeneity of structural fractures.the stochastic simulation can be realized gradually by the steps from large scale to small scale.Large-scale discrete networks are fault networks that can be identified by earthquakes.In the simulation process,according to the fractal characteristics of the fault.the fracture size and density of the ant body are tracked,and the meso-small scale fracture simulation is carried out.Finally,the discrete fracture network model is obtained.Based on the discrete fracture network model,the fracture porosity model and the fracture permeability spatial distribution model are established by the sequential Gao Si simulation method.Under the constraints of these models,the reserves of reservoirs in the study area are obtained by using petrel software and volume method. |
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