基于集合卡尔曼滤波算法刻画低渗透砂岩储层的相对高渗透条带

Characterization for relatively high-permeability zones in low-permeability sandstone reservoir based on ensemble Kalman filter algorithm

随着低渗透砂岩油藏进入开发中后期,长期注水开发使井间易形成相对高渗透条带,增强了储层非均质性,导致生产井水窜,开发效果差。相对高渗透条带内部经过水洗,储层物性得以改善,而其外部储层动用程度低,易形成剩余油富集区,因此准确刻画相对高渗透条带形态与展布是低渗透砂岩储层剩余油分布预测与挖潜的关键。为此,利用开发井的动、静态资料,结合随机模拟得到的储层参数模型,利用集合卡尔曼滤波算法,实现了针对地质属性模型与油藏数值模拟的迭代与更新,使储层参数模型不断吸收并融合油藏内开发井动态生产数据,最终得到能够反映不同开发阶段储层真实地下地质情况的属性模型。结果表明,利用该算法计算得到的储层渗透率模型可指示储层物性在平面上的差异,从而刻画低渗透砂岩储层相对高渗透条带的发育位置及展布形态,为剩余油分布预测与挖潜奠定基础。

When the low-permeability sandstone reservoirs enter into the middle-late stage of evelopment,the relativehigh-permeability zones are easy to be formed between wells and the heterogeneity of reservoirs is enhanced because of the long-term water injection,which results in serious water coning and poor development effect. After washing in the relative？ ly high-permeability zones,the physical properties of reservoirs are improved,and the remaining oil enrichment area can be easily formed in the external reservoirs due to the low degree of production. Accurate description on the state and distri？bution of the relatively high-permeability zones is the key of remaining oil prediction and tapping in the low-permeability sandstone reservoirs. Based on dynamic-static development data of the production wells,the reservoir parameter model can be established combined with the stochastic imulation. Ensemble Kalman filter algorithm was applied to achieving itera？tion and updating of the eological attribution model and the numerical simulation. The attribution model reflecting real geo？logical conditions at various development stages can be obtained combined with the dynamic production data. The results show that the permeability model gained by this algorithm can point out the discrepancies in physical properties in the plane and identify the position and configuration of the relatively high-permeability zone in the low-permeability sandstone reservoir. It lays a foundation for the predicting and tapping of the residual oil istribution.