德惠断陷致密气产能主控因素分析与压裂技术优化

Analysis of main controlling factors of tight gas productivity and optimization of fracturing technology in Dehui fault depression

德惠断陷致密气藏储集层埋藏深、纵向跨度大、孔喉连通性差,高密度完井体积压裂技术虽实现了效益开发,但存在不同井间压后产能效果差异性大,稳产时间短的难题。通过对已施工井优质储集层厚度、铺砂强度、裂缝复杂程度和水锁伤害等因素与产能关系的分析,明确影响单井产能的主控因素,形成差异性射孔+“三段式”先成缝后成网+多级暂堵转向、防水锁压裂液体系等一系列压裂技术对策。经现场DS80-2井试验,压后第二天见气,见气返排率3.8%,日产气8.5×104 m 3,无阻流量19.2×104 m 3,为同区块同厚度气藏产量最高,见气返排率最低井;较设计产能提产20%,降本19%,达到提产控投的目的,为实现致密气藏高效勘探、效益开发提供了技术支撑。

The tight gas reservoirs in Dehui fault depression have deep burial,large span and pore-throat connectivity.Although the high-density well completion volume fracturing technology has achieved profitable development,there are some problems such as large difference in productivity effect after different well pressure and short stable production time.Through the analysis of the relationship between productivity and the factors such as high-quality reservoir thickness,sand laying strength,crack complexity and water lock damage of constructed well,the main controlling factors affecting the productivity of a single well are identified,and a series of fracturing technical countermeasures were formed,such as differential perforation,“three-stage”first forming fractures and then forming networks,first seam and then networking,multi-stage temporary plugging steering,and waterproof lock fracturing fluid system,etc.The field test of DS80-2 well showed that gas was seen on the second day after pressure,gas flowback rate was 3.8%,daily gas was 8.5×104 m 3,and the open flow rate was 19.2×104 m 3,which was the highest gas production and the lowest gas flowback rate in gas reservoirs with the same thickness in the same block.Compared with the designed production capacity,the production is increased by 20%,and the cost is reduced by 19%,which achieves the purpose of increasing production and controlling investment and provides technical support for realizing efficient exploration and beneficial development of tight gas reservoirs.