复杂断块油气藏三维地质建模技术及其应用--以柴达木盆地南八仙油气田为例

3D geologic modeling for complex fault block oil and gas reservoirs and its application to Nanbaxian oil and gasfield,Qaidam Basin

南八仙油气田是柴达木盆地最为复杂的油气田之一,是典型的长井段多砂层复杂岩性—断块油气田,具有断层类型、断层组合关系复杂,含油气井段长,储层变化大,油气藏类型多样及油气水关系复杂等地质特点。为了厘清该油气田油气水空间分布规律、建立油井注采对应关系、适时指导油气田油气协同开发,采用SKUA-GOCAD软件,以南八仙油气田为研究对象,应用小层精细对比成果为主、地震数据体为辅的基础资料建立三维构造模型、岩相模型和属性模型。经过多方法分析比较,优选出适合南八仙油气田油气水三相流体的建模方法,最终完成数模网格设计及参数粗化和输出,为后续开发方案的制定提供了相应的地质模型。研究结果表明:(1)通过"相控"约束,利用变差函数分析对砂体的认识更加清楚,使地质研究、岩相模拟和物性参数模拟三位一体;(2)利用"趋势"技术,将各类地质认识转化为约束条件,合理模拟小层岩相的空间分布,使模拟结果真实可靠;(3)通过插值的方法,结合油气砂体含油气面积的约束建立含气、含油和含水饱和度模型,构建适合复杂断块油气藏的三相流建模方法。

As one of the most complex fields in Qaidam Basin,Nanbaxian oil and gasfield is a typical complex lithologicfault block field with long hole section and multiple sandstones,and characterized by complicated fault type and fault combination relationship,long oil-and gas-bearing hole section,large reservoir change,multiple reservoir types,and complicated oil-gas-water relationship.In order to clarify some spatial distribution of oil,gas,and water,establish an injectionproduction relationship for oil wells,and provide timely guidance for a coordinated development,the Nanbaxian field was taken as an objective to establish 3 D structural model,lithofacies model,and attribute model by means of SKUA-GOCAD software,based on many data with fine sublayer correlation as the main part and seismic-data volume as the auxiliary part.Then,the modeling method suitable for oil-gas-water three-phase fluid was selected by comparatively analyzing several methods.Finally,the numerical model grid design and the parameter upscaling and output were completed,so as to provide a reliable geologic model for formulating subsequent development scheme.Results show that(1)sandbodies are cognized more definitely by means of variogram analysis under the constraint of"facies control",and consequently geologic research,lithofacies simulation,and physical-property parameter simulation are integrated into together;(2)various geologic understandings are converted into constraint conditions by virtue of the"trend"technology,so that the spatial distribution of sublayer lithofacies can be simulated reasonably,which may make the simulation true and reliable;and(3)by means of an interpolation method under the constraint of the oil-and gas-bearing area of sandbodies,the models of gas-,oil-,and water-saturation are established and the three-phase fluid modeling method suitable for complex fault block oil and gas reservoirs is developed.