阵列声波测井资料在吐哈油田致密砂岩气层识别中的应用

吐哈盆地致密砂岩储层具有孔隙度低、渗透性差、孔隙结构复杂等特点,利用常规测井资料难以对储层含气性进行有效评价。以研究区致密砂岩声学特征实验为基础,分析岩样在饱含气状态、饱和水状态下纵波速度和横波速度等参数的变化规律,实验为利用阵列声波测井资料所提取纵、横波时差和常规测井资料计算地层的泊松比、体积压缩系数等参数进行气层识别提供了理论基础。通过储层岩心声学物理试验研究证明,地层在高含气饱和度情况下体积压缩系数和泊松比对含气饱和度变化较敏感;根据阵列声波测井资料计算得到的泊松比曲线和体积压缩系数曲线交会可以直观识别气层。给出的解释实例证实了在吐哈盆地致密砂岩储层利用泊松比与体积压缩系数交会法识别气层的实用性。

The Application of Array Acoustic Wave Data to Tight Sandstone Gas Reservoir in Tuha Oilfield

Low porosity,poor permeability and complicate pore structure are the most obvious characteristics of Tuha basin tight sandstone reservoir,so it is difficult to make an effective reservoir evaluation with conventional log data.Based on the acoustic characteristics experiments of the tight sandstone,analysed are the change rules of P-wave(compressional wave) and S-wave(shear wave) and other parameters of core samples under the conditions of saturated water and saturated gas.DTS and DTC are acquired from array acoustic log data;Bulk density is obtained from density log data.And the DTS,DTC and bulk density are used to calculate the Poisson’s ratio and bulk compressibility coefficient which are effective parameters in gas reservoir recognition.The core acoustic physics experiments prove that the Poisson’s ratio and bulk compressibility coefficient are sensitive to changes of gas-bearing saturation under the condition of higher gas-bearing saturation.The Poinsson’s ratio and bulk compressibility coefficient crossplot may virtually identify the gas reservoir,and is better used in the tight sandstone reservoir in Tuha oilfield.