复杂孔隙结构碳酸盐岩储层建模--以伊拉克米桑油田群B油田M组为例

伊拉克米桑油田群B油田M组为一套复杂孔隙结构缓坡碳酸盐岩台地相储层,受成岩作用影响非均质性强,单井产能差异明显。为了表征优质储层在三维空间的展布,指导新井井位部署,在采用流动层段指标法(FZI)对取心井进行岩石类型划分,通过“决策树”算法实现岩石类型由取心井到非取心井的推广的基础上,基于传统碎屑岩“相控建模”思路,将每类岩石类型定义为一种“沉积-成岩相”,建立三维岩石类型模型,进而根据相控约束建立孔隙度模型,基于岩石类型划分确定的孔渗关系建立渗透率模型,考虑M油藏表现为低阻高矿化度的特征,采用J函数建立了饱和度模型。结果表明,采用岩石类型协同建立的属性模型用于数值模拟,未做历史拟合的情况下,压力、含水率和日产油等指标与历史数据吻合率高达67%以上,表明地质模型能够体现地下油藏的真实流动状态。这种方法对于埋藏较深、成岩作用较强、低电阻率及高矿化度的碳酸盐岩油藏尤为适用。

Complex pore structure geological modeling of carbonate reservoirs: a case study of M formation of B oilfield in Missan Oilfields, Iraq

Complex pore structure carbonate ramp platform reservoir developed in the M formation of B oilfield in Missan oilfields, Iraq. The reservoir is affected by multi-diagenesis, which caused the reservoir with strong heterogeneity, and the wells with significant difference in productivity. In order to characterize the distribution of the high-quality reservoir in three dimensional, and guide the new well deployment, the rock types were classified by using flow zone index (FZI) method for coring wells, and expanding to the un-coring wells by "decision tree" algorithm. Based on the traditional sedimentary facies-controlled modeling method, each rock type was defined as one "sedimentary-diagenesis facies , prosity model was finally built based on the coordinated constraint of rock type, and the permeability model was built by the correlation of porosity-permeability of each rock type. Since the M reservoir is characterized by low resistance and high salinity, the water saturation model was built by J function. The result shows that the properties models were built by correlation with rock types for numerical simulation, without history matching, the index of pressure, water cut, and daily oil are all well consistent with the historical data, and the coincident rate is above 67%. It indicated that the geological model can reflect the real flow state in the underground conditions. This method is particularly applicable to carbonate reservoirs with strong diagenesis, low resistivity, high salinity and deep burial depth.