新型产量递减方程的建立及渗流理论基础——以吐哈油田非常规油藏为例

Establishment of a New Production Decline Equation and Its Theoretical Basis:A Case Study of Unconventional Reservoirs in Tuha Oilfield

针对目前广泛应用于非常规油气藏的Duong产量递减模型和修正Duong产量递减模型,特征参数定义不正确、自变量不能取0、数学模型缺乏渗流理论基础等问题,提出了通过改进油相相对渗透率数学模型,结合适用性较强的水相相渗关系式和Welge方程,得到一种新型产量递减方程。新型产量递减方程在形式上与修正Duong产量递减模型相似,且当特征参数A为0时,可转化为Arps产量递减方程,表明新型产量递减方程为新型广义产量递减方程。新型产量递减方程在马56区块条湖组凝灰岩致密油藏的应用效果较好,可为其他同类型非常规油藏提供借鉴。

The Duong production decline model and modified Duong production decline model widely used for unconventional oil and gas reservoirs are disadvantageous in some aspects,such as incorrect definitions of characteristic parameters,inability to take zero as an independent variable,and lack of flow theoretical basis as a mathematical model.To address these problems,a new production decline equation was proposed by improving the mathematical model of relative permeability of oil phase in fractured reservoirs,and integrating the more applicable water phase relative permeability relational expression and the Welge equation.The new equation is similar in form to the modified Duong model,and can be transformed into the Arps production decline equation when the characteristic parameter A is zero,indicating that the new equation is a generalized production decline equation.The application of the new equation to the tight tuff oil reservoir of the Tiaohu formation in Block Ma56 of Tuha oilfield demonstrated a favorable effect,providing a valuable reference for similar unconventional reservoirs.