气藏水平井生产系统动态分析模型

对于水平井开发气藏，其生产系统由气藏内渗流和水平井井筒内流动两部分所组成。首先仿造采油指数的定义来定义压力平方形式下的采气指数，分别建立了气藏渗流及水平井筒流动的数学模型，该模型具有压力平方的形式，然后应用体积平衡原理将气藏内流动和井筒内流动联系起来，建立了产量耦合下生产系统分析模型，该模型实际上是水平气井的流入流出动态分析模型，分为层流、光滑管壁紊流、粗糙管壁紊流3种流态，推导出气藏水平井的产量随位置变化的关系式，并分析讨论了管壁相对粗糙度对气藏水平井产能的影响，在考虑水平井水平段内摩阻的情况下，实例分析了气藏水平井的流入流出动态关系。这为钻井工程、描述水平井流入流出动态、评价水平井产能、确定合理生产制度和管壁相对粗糙度对气藏水平井产能的影响提供了可靠的手段和方法。

PERFORMANCE ANALYSING MODEL OF PRODUCTION SYSTEM WITH HORIZONTAL WELLS FOR GAS RESERVOIRS

As for the gas reservoirs developed by horizontal wells, the production system consists of the 2 parts i.e. the percolation in the gas reservoir and the flow in the borehole of the horizontal well. First, the gas productivity index in the form of pressure square is defined following the definition of the oil productivity index, and the mathematical models are established respectively for the percolation in the gas reservoir and the flow in the borehole of the horizontal wells. The models have the form of pressure square. Then, with the volume balance principle the flow in the gas reservoir is correlated with the flow in the borehole, and the analyzing model of production system is developed under the production match. The model is the performance analyzing model of inflow and outflow for horizontal gas wells, covering 3 flowing states of laminar flow, velvet turbulence and granulate turbulence. The relational expression of production variation with position variation is derived for horizontal wells of the gas reservoir. The influence of relative roughness of the borehole on the productivity of horizontal wells is analyzed and discussed. Considering the internal friction in the horizontal section of the horizontal well, the performance relation of inflow and outflow is analyzed with real cases for horizontal wells of the gas reservoir. The study provides the reliable tools for drilling engineering, describing the performance of inflow and outflow for horizontal wells, evaluating the productivity of horizontal wells, deciding the seasonable production system, and determining the influence of relative roughness of borehole on the productivity of horizontal wells.