基于净毛比反演模型的河道砂体厚度高精度预测及应用

High-precision Prediction and Application of Channel Sand Body Thickness Based on Net-to-gross Ratio Inversion Model

渤海湾盆地新近系明化镇组浅水三角洲油气藏是渤海油田近年来主要的油气勘探开发对象。浅水三角洲沉积具有单砂体厚度薄、横向厚度变化快、纵向多期河道砂体频繁叠置的特征,储层厚度精细预测难度大,严重制约了油田调整挖潜。针对以上问题,以渤中B油田为例,依据储层地质学理论,利用钻井、录井、测井及地震等资料,创新提出一种基于净毛比地质模型的砂体净厚度反演计算方法。结果表明,研究区明化镇组下段主力砂体地震包络厚度与储层厚度相当,能够较真实地反映地下实际储层厚度。随着储层厚度变大,地震振幅由弱变强再变弱,且在储层厚度一定条件下,净毛比是影响地震振幅的主要因素。采用基于净毛比反演模型的河道砂体厚度预测方法,可有效实现砂体净厚度精细预测,准确率高达83%。该研究成果有效指导了油田开发中后期内部调整挖潜。

The shallow-water delta reservoirs of the Neogene Minghuazhen Formation in the Bohai Bay Basin are the main object of oil and gas exploration and development in the Bohai Oilfield in recent years.Shallow-water delta deposits are characterized by thin single sand bodies,rapid change in lateral thickness,and frequent vertical superimposition of multi-stage channel sand bodies.It is difficult to accurately predict the reservoir thickness,which seriously restricts oilfield adjustment and potential tapping.In response to the above problems,taking Bozhong B Oilfield as an example,an inversion calculation method for the net thickness of sand bodies based on net-to-gross ratio geological model was proposed innovatively according to reservoir ge-ology theory and using drilling,logging,and seismic data.The results show that the seismic envelope thickness of the main sand bodies in the lower section of the Minghuazhen Formation in the study area is equivalent to the reservoir thickness,and can truly reflect the actual underground reservoir thickness.As the reservoir thickness becomes larger,the seismic amplitude changes from weak to strong and then to weak.Under the condition of a certain reservoir thickness,the net-to-gross ratio is the main factor affecting the seismic amplitude.The prediction method for channel sand body thickness based on the net-to-gross ratio inversion model can effectively achieve precise prediction of the net thickness of the sand bodies,with an accuracy of up to 83%.The research results effectively guide internal adjustments and potential tapping in the middle and later stages of oilfield development.