Modified Fetkovich Type Curve Enhances Type Well Construction for Horizontal Wells with Multiple Fractures

摘要

This paper presents a new type curve that can be used to estimate reservoir and completion properties and forecast future production from multi-fractured wells in unconventional, low-permeability reservoirs. In addition, we present a methodology to construct statistical typical well production profiles (type wells) over a complete range of probabilities, including P90, P50, P10 type wells. The type curve is a modification of the familiar Fetkovich type curve, with the transient stems having Arps b-factors from 1 to 4, and the boundary-dominated flow (BDF) stems with b-factors varying from 0 to 1. This new type curve allows us to analyze transient data other than linear flow (b = 2) and to determine the b-factor for BDF based on loglog rate-time plots. We constructed the type curve using the same definitions of dimensionless time and rate variables as in the familiar Wattenbarger type curve for transient linear flow followed by BDF. However, we included many transient and BDF stems and transformed and generalized that type curve into a form similar to the Fetkovich type curve. From a type curve match, we can estimate apparent or effective matrix permeability and an apparent average fracture half-length. Given these parameters and other more readily available parameters (e.g., lateral length, number of fracture stages) we can then scale a well’s production profile to a chosen set of reference conditions. Based on the shape of the production profile (dominated by transient and BDF b-factors), we can place all the wells from a given data set into a small number of individual “bins.” We can then construct type wells for each bin. To forecast future production, we can select appropriate design lateral lengths, fracture half-lengths, stage spacing, and mean or other permeabilities determined from analysis of field data.