工程参数对L区煤层气直井产量影响的定量研究

Quantitative analysis on the effect of engineering paramters on production rate of CBM vertical well in Block L

针对煤层气产量影响因素以地质因素定性分析为主的现状,提出从工程角度研究工程参数对产量影响的思路,即从钻完井、压裂、排采等3个工程环节出发,先用灰色关联分析筛选出与产量关联的参数,再用相关性分析剔除"共线"参数,最后建立产量与工程参数间的数学模型,评价各工程参数对煤层气井产量的影响。通过分析L区49口井实际产量发现,各工程参数对产量影响程度为:降液速度?压裂液量?射孔厚度?累产水量?关井时间?浸泡时间?压裂排量?见气时间?完钻井深?见气套压。结合开发效果分析认为,排采速度过快和压裂裂缝沟通灰岩含水层是导致L区产量不理想的主要原因,与实际相符。结果表明,从工程角度分析不同工程参数对煤层气井产量的影响程度是可行的,为煤层气产量主控因素分析提供了一种新的研究思路。

At present, qualitative analysis on geologic factors is the dominant way to study the infuential factors of coalbed meth-ane （CBM） production rate. In this paper, it was proposed to analyze the effect of engineering parameters on production rate from the viewpoint of engineering. Firstly, the parameters related to production rate are screened out by means of grey correlative analysis based on three engineering sectors （i.e. well drilling and completion, fracturing and production）. Secondly, the collinear parameters are de-leted by means of correlation analysis. And fnally, the mathematical model is established for the relation between production rate and engineering parameters, so as to evaluate the effect of engineering parameters on CBM well production rate. The real production rate of 49 wells in Block L was investigated. According to the effect on production rate, the engineering parameters rank in a descending order of liquid reduction rate, fracturing fuid volume, perforation thickness, cumulative water production, shut-in time, soak time, fracturing displacement, gas breakthrough time, total depth, and gas breakthrough casing pressure. The development results were analyzed, and it is shown that the unsatisfying production rate in Block L is mainly caused by high production rate and limestone aquifers connected by induced fractures, which is in accordance with the real situations. As concluded, it is feasible to analyze the effect of engineering parameters on production rate from the viewpoint of engineering, and it provides a new approach for analyzing the main control factors of CBM production rate.