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在低渗透油气藏中,沿最小水平主应力方向上钻水平井,可以产生多条横向人工裂缝以提高油气井产能。影响多裂缝压裂水平井产能的主要因素因油藏和裂缝性质,以及井眼轨迹而异。目前尚无一个简单而准确的数学模型来评价和优化这类井的产能,而这正是油藏工程师所迫切需要的。在研究多裂缝压裂油气井现有的分析模型后发现,这些模型描述油井的性能在精度上达不到要求。本文提出了一个简单的分析模型可以更好地描述多裂缝压裂水平井的产能。新模型与储层非裂缝区的径向流、裂缝区流向裂缝的线性流、裂缝中的线性流,以及裂缝中流向水平井井眼的径向流相耦合。该模型可以模拟储层裂缝性区域中任意形状储层截面流体的拟稳定流动状态。在两个实例的研究中发现,新模型所给出的产量与实际产量之间的误差小于5%。本文给油藏工程师们提供了一个简单准确的工具来预测、评价和优化多裂缝压裂水平油气井的产能。
In low-permeability reservoirs, horizontal wells are drilled along the direction of the minimum horizontal principal stress, so that a number of horizontal artificial fractures can be generated to increase the productivity of oil and gas wells. The main factors that affect the productivity of multi-fractured fractured horizontal wells vary with the nature of the reservoirs and fractures and the trajectory of the wellbore. At present, there is no simple and accurate mathematical model to evaluate and optimize the productivity of such wells, which is urgently needed by reservoir engineers. After studying the existing analytical models of multi-fractured fractured wells, they found that the performance of these models in describing fractured wells is not accurate enough. This paper presents a simple analytical model that better describes the productivity of multi-fractured fractured horizontal wells. The new model is coupled with the radial flow in the non-fractured zone of the reservoir, the linear flow in the fracture zone to the fracture, the linear flow in the fracture, and the radial flow in the fracture to the horizontal wellbore. The model can simulate the quasi-steady-state flow of fluid in any section of the reservoir in the fractured zone. In two case studies, it was found that the error between the yield given by the new model and the actual yield was less than 5%. This paper gives reservoir engineers a simple and accurate tool to predict, evaluate and optimize the productivity of multi-fracture fractured horizontal wells.