高陡构造背景下油气层有效厚度的确定  

Estimation on the net pay thickness in high steep structural zones

作　　者：徐诗雨 林怡 贾松[1] 杨京 杨帆[1] Xu Shiyu;Lin Yi;Jia Song;Yang Jing;Yang Fan(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院

出　　处：《天然气勘探与开发》2022年第1期15-21,共7页Natural Gas Exploration and Development

基　　金：四川省科技计划项目(编号:2017JY0048)。

摘　　要：在应用容积法估算石油天然气地质储量的时候,油气层有效厚度是计算过程中的重要参数之一。该参数的准确性对最终计算得出的油气地质储量的可靠性影响极大。尤其是在类似于四川盆地东部地区的高陡构造背景下实施的定向井,测井解释的垂厚在井眼轨迹和构造倾角的影响下与铅垂厚度差异较大,如果此时直接将测井解释的垂厚作为容积法的油气层有效厚度参数代入地质储量计算公式中,往往会出现最终的地质储量估算结果与实际的储量数据误差较大的问题。本次工作根据容积法地质储量估算原理,结合实际地质情况建立数学模型,运用地球物理的解释成果,推导出可直接代入容积法估算地质储量公式中的油气层有效厚度参数。研究结果表明:①井眼轨迹与油气层产状的关系可简化成2种数学模型,基于实际钻井地质情况采用不同的数学模型可确定容积法中的油气层有效厚度参数;②应用该方法得出的油气层有效厚度参数代入地质储量计算公式中可有效消除井眼轨迹、构造倾角等参数对计算结果的影响,简单易行,可大幅提高地质储量估算的工作效率和最终结果的准确性;③该方法根据具体的地质情况综合建立数学模型,应用于四川盆地东部地区的多个高陡构造气藏的储量估算中,其应用效果良好,适用性强。Net pay thickness is an important parameter for estimating petroleum reserves using the volumetric method because it has a great impact on the credibility of final reserves.As for some directional wells drilled at high steep structural zones in eastern Sichuan Basin,the vertical thickness interpreted by well logging differs greatly from true thickness owing to the influence of wellbore trajectory and dip angle.If this vertical thickness is directly plugged as the net pay thickness into the equation of geologic reserves in the volumetric method,there may be a large error between the estimated and actual data.So,in accordance with the principle of volumetric method and geology,a mathematical model was established.Moreover,some geophysical interpretation data was used to obtain the net pay thickness which could be directly applied to reserve estimation.Results show that(1)the relation between wellbore trajectory and reservoir occurrence may be simplified as two kinds of mathematical model,and which one is feasible to estimate the net pay thickness depends on actual drilling geology;(2)the influence of wellbore trajectory and dip angle on the estimation could be effectively alleviated using this simple method,and the computational efficiency and credibility could be greatly improved;and(3)the established mathematical model based on actual geology may be validated using reserve estimation for several gas reservoirs in high steep structural zones in eastern basin.

关 键 词：油气层有效厚度 容积法 铅垂厚度 高陡构造 定向井 罗家寨气田 

分 类 号：P618.13[天文地球—矿床学]