用灰色模型预测水力压裂缝导流能力

Prediction of conductivity of hydraulic fracturing induced fractures with gray models

杨宇 孙致学 郭春华

Yang Y? Sun Zhixue Guo Chunhua

压裂后裂缝的导流能力直接关系着压裂缝的渗流能力,是客观评价压裂效果的重要指标之一。在分析用不稳定试井计算人工压裂井的裂缝导流能力的前提和方法后,结合四川盆地川西地区新场气田的应用实例,提出用偏相关分析方法,优选影响导流能力水力压裂的层厚、声波时差、泥质含量、加砂量、施工排量、前置液量等6项地层参数和施工参数,并在此基础上,引入GM(1,)模型进行压裂缝导流能力的预测,提高了预测精度。用此方法也可进行裂缝半长和增产倍数的预测。但由于增产倍数受到表皮系数等无法预先估算因素的影响,预测精度较差,相对而言,用裂缝导流能力作为评价压裂效果的指标更具有客观性。

Fracture conductivity directly influences productivity of fractured formation and is an important index for evaluation of fracturing. This paper analyzes the prerequisites and methods to calculate conductivity of hydraulic fractures through transient test. Taking Xinchang gasfield in Sichuan basin as an example,using partial correlation method,formation and operational parameters that influence conductivity of hydraulic fractures including formation thickness,interval transit time, shale content, proppant content, pump output and preflush volume are optimized.GM(1,) gray model is introduced to increase the accuracy of conductivity prediction.This method can also be used to predict fracture half-length and production gain factor. The prediction accuracy of production gain factor, however, is poor due to the influences of unpredictable factors such as skin.Therefore fracture conductivity is relatively suitable for evaluation of fracturing effects.

10.11743/ogg20040121