理想充填油气层保护技术在吐哈油田的研究与应用

Study and Application of Ideal Packing Formation Protection Technology in Tuha Oilfield

理想充填保护油气层技术是根据d90(累积粒度分布曲线中累积体积分数为90%的颗粒直径)规则,通过综合考虑整个地层孔喉尺寸,借助于理想充填软件优选出与地层孔喉相匹配的一组完整的暂堵剂粒径分布序列,可实现对孔喉的有效暂堵和保护。根据吐哈油田各重点区块的储层特性,应用理想充填油气层保护技术,对丘陵、温米和鄯善等近十二个重点区块的钻井液暂堵方案进行了优化设计。通过使用自主开发的理想充填暂堵软件,将1000目、600目、100目3种Ca CO3暂堵剂按质量比2∶13∶5复配,可使钻井液颗粒的d90(110.92μm)大于储层的最大孔喉尺寸(dmax=80.33μm),可有效封堵储层中各种尺寸的孔喉。复配暂堵剂加量为3%时,钻井液流变参数变化较小,滤失量降低,储层岩心的渗透率恢复值可从30%左右增至80%以上,储层保护效果较好。该技术在吐哈油田20口井进行了现场应用,实验井日产液量较邻井提高45%以上,平均含水率18%。

Ideal packing technology was a new reservoir protecting technology,which was based on d90(particle diameter with accumulation of 90% volume fraction on the size composition of accumulated distribution curve)rule. By considering the whole formation pore throat size,temporary plugging agent with suitable particle size could be optimized by this technology and achieve better reservoir protecting effect. Based on the characteristic of reservoirs of major blocks in Tuha oilfield,the ideal packing technology was applied to optimize temporary plugging projects of twelve blocks for protecting the reservoirs,including Qiuling,Wenmi,Shanshan and so on. Using a self-developed ideal packing temporary blocking software,a combination of three temporary plugging agents with 1000,600 and 100 mesh in mass ratio 2∶13∶5 could make d90 of the particle in drilling fluid(110.92 μm)larger than the maximum pore size of reservoir(dmax=80.33 μm),which could effectively plug pore throat with various sizes in reservoir. The experiment results showed that the optimized temporary plugging agent could improve the buildup of core permeability and reduce the filter loss without impacting the rheology of the drilling fluids. The appropriate amount of the compound temporary plugging agents was 3%. The reservoir permeability recovery value improved from 30% to more than 80%,which had a good reservoir protection effect. This technology was applied in 20 wells in Tuha oilfield,as a result,the daily fluid production of testing wells increased more than 45% than that of adjacent wells,and the average water content was 18%.