鄂尔多斯盆地延长组下组合储层评价与有效开发技术策略

Reservoir Evaluation and Effective Development Technology in Lower Yanchang Formation

鄂尔多斯盆地延长组下组合资源潜力巨大,但储层致密,导致开发效果差,储量难动用。针对此问题,以吴仓堡地区长9储层为切入点,通过大量分析化验数据,应用五元综合分类系数法对下组合储层进行了分类评价,并结合开发数据对有效开发方式进行了分析。结果表明,吴仓堡地区长9储层综合评价系数为3.01,属于低渗透Ⅲ类储层,其他各区块下组合储层均为Ⅲ类或Ⅳ类储层,以Ⅳ类储层为主,应用常规技术难以取得突破,动用难度大。各类开发技术的应用效果对比表明,注水可以有效改善下组合储层的开发效果,且注水时机越早效果越好;水平井开发下组合不但产量高,而且稳产能力优于常规井;应用缝网压裂的开发井其产量约为常规压裂井的2倍;表明"注水+水平井+缝网压裂"的开发技术模式适用于高效开发下组合难动用储量,应大规模推广应用。

In the Ordos Basin,the resources of the lower Yanchang Formation is huge but difficult to be developed and produced,because of the tight reservoir. To solve the problem,we took the Chang 9 reservoir in Wucangbao area as beginning point,based on analyzing a large number of test data,we conducted classified evaluation on the low assemblages by applying the ＂five yuan synthetic classification coefficient＂,and got insight into the effective development ways on the basis of development data. Results whoed that the comprehensive evaluation coefficient of Chang 9 reservoir in the area was 3. 01 and the reservoir belonged to low-permeability Class III reservoir,while other assemblages of other blocks were Class III or Class IV ones,which were dominated by Class IV ones. Conventional technology is difficult to make breakthrough and hard to be used for producing. Comparison of the application of all development technologies revealed that water injection could effectively improve development effect of low assemblages. The earlier we injected water,the better the result was. Horizontal well development could not only reach high yield,but could keep more stable production compared with conventional wells. The production of the wells with fracture network fracturing doubled that of the wells with traditional fracturing. It was indicated that the development mode of＂water injection＋horizontal well development＋fracture network fracturing＂was applicable for the reserves difficult to be produced in low assemblages and deserved large-scale application.