成因与演化信息约束的辫状河储层地质建模——以委内瑞拉奥里诺科重油带M区块为例

委内瑞拉奥里诺科重油带位于全球规模最大的重油富集区，地质储量丰富，开采潜力大。但是，由于该区主要产油层段是以砂质辫状河类型为主的河流相沉积，具有平面相变快、纵向上砂体叠置的特点，储层内部非均质性强，严重制约了后续的产量接替和开发方案实施。为此，以M区块Oficina组下部为例，根据岩心、测井、地震响应等特征，共识别和划分出复合心滩坝、辫状河道沉积、废弃河道沉积、残余洪泛泥岩沉积四种主要成因单元；在沉积模式的指导下，提取地层切片，分析成因单元的演化过程；将这些信息转化为控制地质建模的概率体，以水平井和直井识别结果为硬数据，建立由成因与演化信息约束的地质模型。将该模型用于开发井设计，使水平井油层钻遇率提高至95%以上，表明方法应用效果良好。

Geological modeling of braided river reservoir based on genesis and evolution: a case study on block M in Orinoco Heavy Oil Belt,Venezuela

The Orinoco Heavy Oil Belt in Venezuela is the largest heavy oil accumulation area in the world.It is rich in geological reserves and has a huge exploitation potential.However,because the primary oil pay zone in the area is almost fluvial deposits of sandy braided river,it is characterized by laterally fast facies change and vertically complex superimposition of sand bodies,resulting in serious heterogeneity inside the reservoir,and restricting the following production and the implementation of the development plan.Taking the lower Oficina formation in block M as a case,according to the cores,well logging and seismic data,four main genetic units were identified and summarized including compound bars,braided channels,abandoned channels and residual floodplain mudstone.Under the gui-dance of a sedimentary conceptual model,the strata slicing method was used to extract and analyze the evolution process of the genetic units over time.This information extracted was transformed into a probability volume to control the geological modeling process.Taking the identified results of horizontal and vertical wells as hard data,a final geological model controlled by genesis and evolution information was established under the constraint of the probability volume.The drill-in rate by horizontal wells has been increased to more than 95% after the model was applied in field operation,indicating a good application effect.