利用横波反射技术定量计算水平井储层边界

Quantitative Calculation of Horizontal Well Reservoir Boundary Using Shear Wave Reflection Technique

低渗透率砾岩油藏采用水平井与体积压裂技术进行开发,而储层边界是井眼轨迹评价和压裂设计的重要参数。利用地质建模计算储层边界受到电阻率与伽马反演影响,储层边界计算精度低,难以准确定量化计算。准噶尔盆地低渗透率砾岩油藏地层倾角小、储盖层波阻抗差异大、水平井轨迹角度接近90°、偶极横波传播方向与储层边界垂直、储层边界偶极横波反射信号强烈,根据这些规律,提出利用横波反射技术定量计算水平井储层边界的方法。该方法仅用正交偶极声波数据即可准确计算水平井储层边界距井眼的距离,结合地层产状、厚度、井眼轨迹,计算储层边界垂直深度,形成水平井储层、井眼轨迹、上下隔层垂向剖面,能够准确评价水平井储层和井眼轨迹,为低渗透率砾岩油藏效益开发提供量化依据。

Horizontal wells and volumetric fracturing techniques are used to develop low permeability conglomerate reservoirs.Boundaries of reservoir is key parameters for the evaluation of well configuration and hydraulic fracturing design.Geological modeling,resistivity inversion,and gamma inversion are affected by the modeling methods and by the depth of investigation,and the accuracy of boundary calculation is low,making it hard to quantify the boundaries.In the low permeability reservoirs in the Junggar basin,the formation inclination angles are small;the wave impedances contrast of reservoir and cap rock are large;horizontal well trajectory angles are nearly 90°.In this environment,the propagation of dipole shear wave is perpendicular to reservoir boundaries,with strong reflection signals at boundaries.Based on these characteristics,a method of quantitative calculation of reservoir boundary in horizontal wells by using shear wave reflection technique is proposed.This method can accurately calculate the distance between horizontal wellbores and the boundaries only based on orthogonal dipole acoustic wave data.Then,based on formation occurrence,thickness,and well configuration,altitudes of reservoir boundaries can be obtained.As a result,vertical profiles of horizontal well reservoir,well configuration,and upper and lower interlayers can be determined.The study improves the evaluation accuracy of horizontal well reservoir and well configurations,and it provides quantitative references for the commercial development of low permeability conglomerate reservoirs.