关键词: 阶梯水平井, 断块油藏, 地层渗流, 井筒管流, 质量守恒原理, 微元线汇理论

Abstract:

Base on theories related to fluid mechanics and seepage mechanics, a mathematical analysis model that couples the wellbore conduit flow and formation seepage was established to deal with the situation that a stepped horizontal well traverses three independent fault-block oil layers. Based on the mass conservation law and micro-unit line-congruence theory, the model analyzed the influence of inflow on the pressure drop within wellbore for horizontal production sections and educed an equation to calculate the pressure drop of a production section in stepped horizontal wellbore. A method to calculate the pressure drop under the condition of different curvature radius was proposed for linking sections of various oil layers. Meanwhile, since different fault-block oil layers traversed by a stepped horizontal well have different production capacity, the resolution based on a mathematical model was educed along with a corresponding computing program. With the utilization of this analysis model, the distribution of on-way pressure of stepped horizontal wellbore as well as the output at different positions could be predicted. The analog computation indicated that the output was influenced both by the production capacity of each oil layer and by the flow friction of horizontal wellbore, moreover, it is more favorable to exploitation if oil layers with better and worse physical properties were located, respectively, at the heel and toe of horizontal wells.

Key words: stepped horizontal well, fault-block reservoir, formation seepage, wellbore conduit flow, mass conservation law, micro-unit line-congruence theory