非均质低渗凝析气藏压裂后低效原因分析及改进措施.docVIP

非均质低渗凝析气藏压裂后低效原因分析 Analysis on the Inefficiency Cause and Improvement Measures for Fracturing of the Heterogeneous Low-permeable Condensate Gas Reservoir Abstract: In allusion to the problem that the stimulation effect of the fracturing for most of the heterogeneous low-permeable condensate gas reservoir is negligible, the paper conduct a research on the fracturing design, fracturing operation and the flowback process of one typical heterogeneous low-permeable condensate gas reservoir. The results show that the phase behavior, hydrocarbon enrichment regularity, the radial and vertical distribution of oil-and gas-bearing sand for the gas reservoir have not been made clear, and the fracturing design is lack of pertinence. The backflow velocity of fracturing fluid and the reservoir pollution caused by retrograde condensate during backflow period lead to the decrease of the flow conductivity and the stimulation effect of fracturing. So the improvement measures for enhance the stimulation effect of fracturing has been developed in this research, and the measures include that enhancing the research on the phase behavior and the heterogeneity before fracturing, electing well and layer scientifically, optimizing the fracturing scale, optimizing the flowback velocity based on model of deliverability variation caused by the condensation pollution and controlling the drawdown pressure after fracturing. This study can be referred to improve the stimulation effect of the fracturing for condensate gas reservoir. Key words: low permeable condensate gas reservoir; reservoir heterogeneity; phase behavior；fracturing; inefficiency cause; improvement measures 引言 非均质凝析油气藏一般具有埋藏较深、物性差地露压差小、易发生反凝析且储层易受反凝析污染等特点[1-2]；并且受储层非均质影响，气藏形态、厚度、地层流体性质等横向变化大，使得气藏复杂自然产能往往达不到工业开采经济极限[3-5]。水力压裂低渗储层增产有效手段，近年来随着压裂技术的不断完善，压裂改造成功率及压后有效率逐步提高，低渗常规油气藏压裂设计，制约了非均质低渗凝析气藏的增产效果。 本文以某非均质低渗凝析气藏D-2井压后低效为例，该井压裂施工过程压后增产情况，压后低效原因1. D-2井储层特征及完井测试情况 1.1 储层特征 D-2井所在区块储层非均质强，横向连通性差，含油气砂体形态、厚度在横向上变化大。地层异常高压（压力系数1.60）；地温