Type curve analysis for naturally fractured reservoirs (infinite-acting reservoir case): a new approach

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references (leaves 92-95).Issued also on microfiche from Lange Micrographics.This work introduces new type curve solutions for an unfractured well in an infinite-acting naturally fractured reservoir, including wellbore storage and skin effects. Both pseudosteady-state¹ and transient²⁻³ interporosity flow models are studied. The objectives of this work are as follows: First, we generated new type curves for the analysis of pressure drawdown and buildup tests performed in naturally fractured reservoirs. Next, we develop a systematic approach for the analysis and interpretation of well test data taken from naturally fractured reservoirs for both pressure drawdown and buildup tests. Finally, we have to validate our new type curves using field data obtained from the literature and industry sources. It has been shown that semilog analysis methods are sometimes inconclusive for pressure transient analysis of wells completed in naturally fractured reservoirs. This is due to wellbore storage effects which mask the early time "straight-line" that is expected on the semilog plot. The early time trend along with the late time semilog straight-line, is required in order to appropriately characterize the naturally fractured (dual porosity) system. This situation was remedied to a large degree by using log-log methods (i.e., type curves). A further improvement is presented in this work. This improvement was achieved by the introduction of a new dimensionless parameter, α=[]C[], where the use of α as a family parameter for the dimensionless pressure function type curves provides a better resolution of individual data trends. Generally speaking, type curve analysis is constrained by the issue of uniqueness. This issue has been reduced by the use of the derivative function - as well as the second derivative, the pressure integral, the pressure integral derivative functions, as well as combinations of these functions. Using these functions in conjunction with the α - parameter approach, we are more likely to be able to characterize a given naturally fractured reservoir (for the infinite-acting reservoir case). To summarize, the type curves presented in this work (which are created from accepted earlier models), provide greater confidence in the analysis of pressure transient test data