水平井变密度射孔优化设计模型

针对水平井应用过程中容易出现底水脊进、射孔成本过高、射孔易损害套管等问题,基于射孔完井水平井生产流体流动压降分析,研究了油藏流体渗流模型、射孔孔眼流体流动模型、井筒流体流动压力梯度模型以及流动耦合模型,建立了水平井变密度射孔优化设计模型。研究结果表明,通过优化水平井变密度射孔密度分布,可有效地调节水平井生产流体流入剖面,防止底水脊进;变密度射孔可减少射孔的数量,降低射孔成本及射孔对套管的损害程度;初始孔密、原油黏度以及是否射穿污染带等影响变密度射孔孔密分布;初始孔密较大时,射孔密度的变化较大;原油黏度较大时,射孔密度的变化较小;已射穿污染带时射孔密度的变化大于未射穿污染带时射孔密度的变化。同时,初始孔密和原油黏度对井底流压和孔眼压降也有较大的影响。图5参14

Optimized models of variable density perforation in the horizontal well

Aimed at the problems of bottom water coning, high cost of perforation and deterioration of casing tube, the optimized models of variable density perforation for horizontal wells are established after the study of the fluid flow model through porous medium, the perforation flow model, the pressure gradient model of well bore flow and the flow coupling model based on analyzing the production flow pressure dropdown of perforated horizontal wells. The inflow section of horizontal well production fluid can be regulated effectively by optimizing the density distribution of variable density perforation and bottom water coning can be prevented; variable density perforation can decrease the perforation density, so the cost of perforation and damage of casing also drop down; the initial perforation density, the viscosity of crude oil as well as the perforation condition of polluted zone has a prominent influence on the density distribution. The larger the initial perforation density, the larger the variation of perforation density; the larger the viscosity of crude oil, the smaller the variation of perforation density; the variation is bigger when the contamination zone is completely perforated than incomplete perforated. Also, the initial perforation density and the viscosity of crude oil also have a large effect on the bottom hole flowing pressure and the drop of pressure in well bore.