New coupled models for transient pressure analysis in low permeability reservoirs.

Abstract: It is shown that the flow in the low permeability medium is nonlinear, which is quite different from the general Darcy flow. In this paper, we first present a survey of methods that has been used to analyze the low permeability well problems for the past 10 years, then we present two new coupled models that behaves better in complex situations. We assume that there are two different zones near the wellbore and the flow characteristics in the inner zone is different from that in the outer zone, and there is an connecting interface between them, as mentioned before, we called them coupled models. In this paper, we also give four different types of the typical curves for four different models and use the methods of alternating iteration algorithm to solve the nonlinear differential equation system. These four different types of the curves will cover the typical problems that will possibly be encountered when exploring the low permeability reservoirs. [Copyright &y& Elsevier]