双重介质致密油藏压裂水平井产能预测模型及参数分析

随着越来越多的致密油藏投入开发,压裂水平井产能的预测也越来越受到重视,但是由于致密油藏存在启动压力梯度和应力敏感效应,一些产能预测公式存在一定的局限性。为此,在研究致密油藏流体流动特征的基础上,考虑了原油在基质内的椭圆流动以及裂缝内的近径向流动,将两个流动区域进行耦合建立了两区渗流模型;同时考虑启动压力梯度、应力敏感效应及缝间干扰问题,推导了致密油藏压裂水平井产能预测公式,并对敏感参数和裂缝参数进行了分析,结果表明:水平井产量与启动压力梯度、应力敏感系数负相关,与裂缝条数、裂缝半长、裂缝导流能力及裂缝间距正相关。该模型全面地考虑了致密油藏特征对产能的影响,对致密油藏开发的压裂施工设计有一定的指导意义。

Productivity Prediction Model and Parameter Analysis for Fractured Horizontal Wells in Double Medium Tight Oil Reservoirs

As more and more tight oil reservoirs are put into development, the productivity prediction of fractured horizontal wells is becoming more and more important. However, due to the existence of threshold pressure gradient and pressure-sensitive effects in tight reservoirs, some productivity prediction formulas have some limitations. For that reason, based on the research of flow characteristic in tight oil reservoir, a two-region oil seepage model was built using the elliptic seepage theory and superposition theory; with a comprehensive consideration of the threshold pressure gradient and the pressure-sensitive effects, a new productivity prediction model for horizontal wells was deduced and the interferences between fractures were considered at the same time, and then the analyses of these parameters suggest that the productivity of fractured horizontal wells are positively related to the threshold pressure gradient and the pressure-sensitive coefficient while negatively related to fracture numbers, fracture lengths, fracture conductivities and fracture spacings, however, these coefficients have their own optimal values, respectively. This model considers how the characters of the tight oil reservoirs influence the productivities sophisticatedly so as to provide some guidance for fracturing design in tight reservoir development.