SF气田水平井分段压裂技术研究

STAGED FRACTURING TECHNOLOGY USED IN HORIZONTAL WELL OF SF RESERVOIR

SF气田蓬莱镇组气藏水平井分段压后平均测试产量为1.23×104m3/d,投产率仅46%,个别井出砂严重堵塞油管,且平均返排率为58.2%,未达到预期开发效果。针对这种情况,亟待深入分析原因,通过深化储层认识和实验研究,认为储层多为砂泥岩互层,非均质性严重,采用均质模型进行裂缝间距优化不尽合理;储层存在中等水敏、较强的水锁伤害导致常规压裂液储层适应性差;水平井分段压裂施工时间长、分段破胶难度大、返排制度不完善是该气田水平井压后产量低、返排效果不理想的主要原因。为此,提出开展水平井液氮伴注、纤维防砂优化、研究各段压后储层增能情况,制定水平井合理的返排制度,在提高返排速率的同时达到防止支撑剂回流,降低储层伤害和安全风险的目的。

The average testing yields is 1. 23 × 104m3/ d and production rate is only 46 %,the average flowback rate is58. 2% and individual wells sand so seriously that block tubing after staged fracturing in horizontal well of Shifang reservoir,the anticipative development results didn't been achieved. According to the situation,through experimental study,the reasons resulted in above problems were found,i. e. serious heterogeneity and sandstone and mudstone alternate layer resulted in crack spacing optimization was not reasonable by using homogeneous model. Moderate water sensitivity and strong water blocking damage existing in container rock resulted in the poor adaptability on conventional fracturing fluid. Long fracturing time in horizontal well,difficult staged gel breaking and imperfect horizontal well flowback system were the main reasons of low production and low flowback rate. In order improve the development effects of SF gas field,some corresponding measures were proposed,such as liquid nitrogen injection,fiber sand prevention technique optimization,working out rational flowback system to increase flowback rate and avoid the backflow of proppant,and reduce reservoir demage.