川西潮坪相裂缝型碳酸盐岩分层酸压井压力动态分析

为全面反映储层分层酸压后复杂的流动特征，针对潮坪相类碳酸盐岩储层，建立了考虑层间窜流的裂缝型碳酸盐岩分层酸压改造井不稳定压力模型，并利用拉氏变换和数值反演得到井底压力动态响应。根据典型曲线划分了流动阶段，分析了层间物性差异、层间窜流、分层改造差异对压力响应的影响规律。结果表明：潮坪相裂缝型碳酸盐岩分层酸压改造储层存在7个流动阶段，同时具有复合储层和多层窜流储层的流动特征；层间物性差异越大，层间窜流及压力导数曲线“凹子”越明显；分层酸压改造程度及改造范围均影响过渡流出现的时间和程度；高渗层流度比越大，过渡流阶段压力导数上升越明显，最终压力导数值为高渗层流度比的一半。本次研究建立的模型提供了一种快速识别储层高渗层改造程度的方法，对多层裂缝型碳酸盐岩的酸压效果评价、分层酸压改造程度的确定具有理论支撑作用。

Pressure transient analysis for separate-layer acid fracturing well of tidal flat fractured carbonate reservoirs in western Sichuan Basin

In order to reflect the complex flow characteristics of reservoir after separate-layer acid fracturing, aiming at tidal flat fractured carbonate reservoir,a pressure transient analysis model considering crossflow for separate-layer acid fracturing wells in fractured carbonate reservoir was established,and the bottom-hole pressure was obtained by Laplace transformation and numerical inversion. According to the type curves of pressure and its derivative,the flow stages were identified and divided,and the effects of interlayer physical property differences, crossflow and separate-layer modification differences on pressure response were analyzed. The results show that there are seven flow stages of tidal flat fractured carbonate reservoir in separate-layer acid fracturing,and the type curve has the flow characteristics of composite model and layered crossflow model. The greater the difference of interlayer properties,the more obvious the crossflow and concave on the pressure derivative curve are. The separate-layer acid fracturing degree and scope both affect the time and scale of transition flow occurrence. The higher the mobility ratio of high-permeability layer is,the more obvious the transition flow stage is,and the pressure derivative value is the half of the mobility ratio of high-permeability layer during outer radial flow stage. The model can provide a method for quickly identifying the acid fracturing degree of high-permeability layer, which can be used to evaluate the acid fracturing effect of multi-layer fractured carbonate reservoir and determine the degree of acid fracturing modification of individual layer.