示踪剂裂缝监测技术在气藏水平井压裂中的应用

Application of tracer fraction monitoring technology on horizontal well fracturing in gas reservoirs

针对现有压裂裂缝监测手段匮乏、成本较高且操作复杂等问题,利用水溶性有机微量物质示踪剂对LX致密气田的分段压裂水平井LX-A井进行了裂缝监测。优选9种不同示踪剂分别注入9个压裂段,通过在压后13天内对不同取样时间的水样中示踪剂产出浓度进行分析,得到了9个层段的动态产水情况及裂缝参数。结果表明,该井第9段先开始返排,返排前期第7、9段压裂液返排占比较高,分别为15%和50%,其他段返排液占比较低且较为接近,均不到10%。返排末期第3、4、7、9段压裂液返排占比较高,分别为13%、17%、13%和30%,其他段返排液占比不到10%;该井改造区裂缝渗透率在0.03~0.16mD,在第1~6段逐渐降低,在第6~9段逐渐升高,第9段渗透率最高;其裂缝半长在30~290m,其中第1~7段,除第5段外,基本呈上升趋势,第8、9段基本相当,均小于第7段。实践证明,示踪剂监测技术能够作为水平井分段压裂裂缝监测的有效手段,为压后效果评估提供参考。

In response to the lack of existing fracturing fraction monitoring methods and their high cost and complex operation,water-soluble organic trace substance tracers were used to monitor the fractures of the segmented fracturing horizontal well LX-A in LX tight gas field.9 different tracers were selected and injected into nine fracturing sections.By analyzing the production concentration of tracers in water samples at different sampling times within 13 days after fracturing,the dynamic water production and fracture parameters of the nine sections were obtained.The results showed that the 9th section of the well begins to flow back.During the early stage of the well's flow back period,the fracturing fluid flow back from the 7th and 9th sections accounted for a relatively high proportion of 15% and 50%,respectively.The flow back from other sections accounted for a relatively low and close proportion of less than 10%.At the end of the backflow stage,the proportion of fracturing fluid flowback in the 3rd,4th,7th and 9th segments was relatively high,at 13%,17%,13% and 30% respectively,the proportion of flowback fluid in other segments was less than 10%.The fracture permeability in the well renovation area ranges from 0.03 to 0.16mD,gradually decreasing in the lst to 6th segments and increasing in the 6th to 9th segments,with the highest permeability in the 9th segment;The half length of its cracks ranges from 30 to 290 meters,with the first to seventh segments showing an upward trend except for the fifth segment,while the eighth and ninth segments were basically equivalent and smaller than the seventh segment.Practice has proven that tracer monitoring technology can serve as an effective means for monitoring segmented fracturing fractures in horizontal wells,providing reference for evaluating post fracturing effects.