吉木萨尔凹陷陆相页岩油储层测井定量解释

Study on Quantitative Well Logging Interpretation of Continental Shale Oil Reservoir in Jimusar Sag

以吉木萨尔凹陷二叠系芦草沟组陆相页岩油为研究对象,采用岩芯刻度测井和数据挖掘两种方法,分上、下甜点分别建立物性、含油性、微观孔隙结构及岩石力学等参数的测井定量解释模型,在矿场应用中储层评价精度得到大幅度提高,均达到85%以上。特别是多条曲线反演的渗透率模型,数据挖掘方法优选出3条测井曲线,既反映了绝对孔隙性对渗透率的贡献,又考虑了微观孔隙结构改造对渗透率的制约,用自然伽马和声波时差曲线分别表征泥质含量和压实胶结作用对渗流路径及渗流阻力的影响,相较于单因素模型,其计算精度提高了25.6%。另外,由于井眼环境、孔隙流体的重力分异以及地层在不同方向上的各向异性,水平井与直井测井曲线存在一定的偏差,基于直井测井曲线响应特征与岩芯分析资料建立的解释模型不能直接应用于水平井的储层评价。针对以上难题,建立两种测量方式测井曲线的转换图版和公式,在测井曲线转换的基础上,可以对水平段的储层进行定量解释。

The continental shale oil of Permian Lucaogou Formation in Jimusar Sag is selected as the research object to establish quantitative well logging interpretation models.Core calibration logging and data mining are used to establish the quantitative well logging interpretation models of physical properties,oil-bearing properties,micro pore structure and rock mechanics respectively according to the upper and lower sweet spot.In the field application of well logging interpretation models,the accuracy of reservoir evaluation has been greatly improved,reaching more than 85%.The three well logging curves are selected by the data mining method with the multi-factor permeability calculation model,not only reflect the contribution of absolute porosity to permeability,but also consider the restriction of micro pore structure transformation on permeability,and two well logging curves of natural gamma ray and acoustic time difference are used to characterize respectively the influence of shale content and compaction-cementation effect on seepage path and seepage resistance.Compared with the single factor model,the calculation accuracy is improved by 25.6%.In addition,due to the following influences such as the borehole environment,the gravity differentiation of pore fluid and the anisotropy of formation in different directions,there is a certain deviation between horizontal and vertical well logging curves.So the quantitative well logging interpretation models based on the response characteristics of vertical well logging curves and core analysis data can not be directly applied to the reservoir evaluation of horizontal wells.In view of the above problems,the conversion chart and calculation formula of well logging curves of two measurement methods are established,and the reservoir of the horizontal section can be quantitatively interpreted.