斜井泥浆侵入仿真及其阵列侧向测井响应数值模拟

为了研究斜井泥浆侵入储层的井周岩石物理特征,采用广义曲线坐标系统模拟斜井泥浆侵入特性,进而研究泥浆侵入过程的阵列侧向测井响应.数值仿真表明,采用广义曲线坐标系消除了笛卡儿坐标系统在斜井边界处网格划分的锯齿现象;储层非均质造成泥浆侵入不均匀,储层渗透性越好,泥浆滤液侵入越深;泥浆滤液侵入使得井周地层饱和度、孔隙水矿化度的分布发生变化,进而造成斜井井周岩石电阻率分布剖面复杂变化;泥浆侵入过程中阵列侧向视电阻率变化以及深浅视电阻率的幅度差异,有效反映了斜井泥浆侵入特性;文中采用了基于Marquardt方法的阵列侧向测井四参数反演,有效恢复了斜井储层侵入剖面,得到了原状地层电阻率.斜井泥浆侵入特征及其阵列侧向测井响应模拟分析,有助于正确认识斜井井周岩石物理特征和利用阵列侧向测井进行斜井储层评价.

Numerical simulation of mud invasion and its array laterolog response in deviated wells

In order to study the petrophysical properties of mud-invaded formation in deviated well, a generalized curvilinear coordinate system is used to simulate the characteristics of mud invasion, and then the array laterolog response during mud invasion is researched. Numerical simulation shows that the phenomena of saw tooth in mesh generation on the border of dip borehole, which is unavoidable in Cartesian coordinate system, can be effectively eliminated in curvilinear coordinate system. The heterogeneity of formation results in non-uniform mud invasion, the better the reservoir permeability is, the more deeply mud filtrate invades. And mud invasion changes the distribution of both fluid saturation and salinity around borehole, thus leading to the complexity of rock resistivity distribution around the deviated well. The variation of apparent resistivity from array laterolog and the difference between its deep and shallow resistivity during mud invasion reflect the characteristics of mud invasion. In this paper a four-parameter inversion of array laterolog based on Marquardt method is adopted to effectively recover the invasion profile and then obtain the original formation resistivity in deviated well. The analysis of invasion characteristics and array laterolog response simulation in deviated well contributes to the correct understanding of petrophysical properties around the well and reservoir evaluation with array laterolog in deviated well.