水力压裂选井选层的快速评价方法

Quickly evaluating method of selecting hydraulic fracturing wells and pay-zones

利用保角变换和Laplace变换,推导无限导流能力垂直裂缝井在不同时间的不稳态产量与累积产量公式,用以预测在水力压裂理想极限情况下的产能,若产能低于经济下限产量,应该放弃压裂。采用该方法,将油层有效渗透率、有效厚度、生产压差及地下原油黏度等作为综合性的储集层物性下限评价指标,可以从油藏及储集层的角度选择压裂井和储集层。该方法在二连盆地乌里雅斯太凹陷的应用结果表明,根据储集层物性下限评价指标,可以快速进行压裂选井、选层。

A specified conformal transformation function and Laplace method are utilized jointly to establish a mathematicalmodel of calculating a hydraulic fracturing well's oil rate and accumulative oil at various producing time under the condition of infinite conductivity, which may be used to select fracturing wells and pay-zones so as to maximize economic profits. After that, the influence of effective permeability, net pay-zone thickness, fluid viscosity and the pressure difference of initial pore pressure to the bottom flowing pressure on the fracturing result is calculated according to the model put forward. Consequently, a comprehensive evaluation index which includes above four parameters is put forward to the base of above calculations, and the result indicates that the fracturing well's oil rate is unchanged with the above comprehensive index kept as a constant while the included four parameters mentioned above may be changed greatly, so that the established index may be used to quickly select the fracturing wells and pay-zones. Overall, the study may be used to perform formation evaluation, fracturing effect evaluation and selecting the optimal fracture length as well.