Interpretation of Multiple Hydraulically Fractured Horizontal Wells

Abstract

Abstract Horizontal wells are ideal in tight reservoirs where economic production cannot be achieved by conventional vertical wells. One of the advantages of a horizontal well over a vertical well is that it can be fractured at a number of positions along its horizontal section. Tight reservoirs generally produce in transient state for a considerable part of their producing life. Therefore accurate transient inflow models are required, not just for well testing purposes, but also for production forecasting. The objective of this study is to determine the number and characteristics of the producing fractures along the horizontal segment of the well. A new analytical model is developed to describe the transient pressure response of a horizontal well intersected by several fractures in anisotropic reservoirs. The fractures along the horizontal wells are assumed to be rectangular and vertical, and either transversal or longitudinal relative to the well direction. They are also of finite conductivity, infinite conductivity, or uniform flux type. It is further assumed that the fractures are fully penetrating (2D Model) or partially penetrating (3D Model), the well is either open or perforated only at fractures. A new set of type curves are developed that include five flow regimes: Bilinear, Linear, Radial, Biradial, and Pseudoradial. New equations have been developed describing the unique characteristics of the five flow regimes. These equations allow us to calculate: the number of active fractures, equivalent fracture conductivity and total system conductivity, equivalent half-fracture length, reservoir directional permeabilities, equivalent skin, and the total skin of the system without using type-curve matching. A step-by-step procedure is provided for calculating reservoir parameters of a multiple hydraulically fractured horizontal well and practical applications are carried out by solving some simulated examples.