致密油藏体积压裂水平井分区复合产能模型

COMPOSITE PRODUCTIVITY MODEL FOR THE VOLUME FRACTURED HORIZONTAL WELL DISTRICTS IN TIGHT OIL RESERVOIRS

水平井体积压裂是实现致密油藏有效开发的关键工程技术手段,对致密油藏体积压裂水平井产能的准确模拟计算为体积压裂参数优化设计和压后生产动态预测提供了参考。基于致密油藏体积压裂水平井生产过程中油藏的实际流动形态特征,将水平井划分三线性流区域,结合Warren-Root模型,考虑储集层启动压力梯度和天然裂缝的影响,建立了致密油藏体积压裂水平井分区复合产能模型。结合现场生产数据验证了模型可靠性,并对产能影响因素进行了分析。结果表明:压后总体产量受到延伸主裂缝的条数、半长和导流能力的影响;启动压力梯度及改造区的弹性储容比和窜流系数对压后中后期产量影响大;未改造区窜流系数和弹性储容比影响后期产量的递减速度。该研究对深化认识致密油藏体积压裂水平井流动规律,完善致密油藏体积压裂渗流理论,提升致密油体积压裂优化设计都具有重要理论意义和实际价值。

Volume fracturing for the horizontal well is the key engineering method to realizing the effective development in tight oil reservoirs,the accurate analog calculation for the productivity of this kind of the horizontal well can offer the references for the optimal design of the volume fracturing data and the production performance prediction after the fracturing.Based on the actual flow pattern characteristics of the oil reservoir during the production process of the volume fractured horizontal well in the tight oil reservoir,the horizontal well was divided into three linear flow regimes.Combined with Warren-Root model,considering the influences of the threshold pressure gradient of the reservoir and the natural fractures,the composite productivity model of the horizontal well districts for the volume fracturing in the tight reservoirs was established.The model reliability was verified by the field production data,and moreover the productivity influencing factors were analyzed.The results show that the overall output after the fractu-ring is subject to the amount,half-length,conductivity of the propagated principal fracture;the productions in the middle and late periods after the fracturing depend much on the threshold pressure gradient,the elastic storativity ratio in the reconstructed area and the interporosity flow coefficient;the interporosity flow coefficient and the elastic storativity ratio in the non-constructed area have effects on the production decline rate in the late period.This studies possess important theoretical and practical significances and actual value for deeply understanding the flow laws of the volume fractured horizontal well,improving the filtration theory of the volume fracturing and promoting the optimal design of the volume fracturing in the tight oil reservoir.