Showing papers by "Michael J. Economides published in 1997"

Fracture-Injection-Test Interpretation: Leakoff Coefficient vs. Permeability

Abstract: Determining the leakoff coefficient from a minifracture pressure decline has become a relatively common industrial procedure. A main assumption of the method, which is often referred to as the Nolte analysis, is a constant leakoff coefficient. Frequently there is no constant leakoff coefficient. The definition of the coefficient is based on a constant pressure differential and a prescribed mode of leakoff. In contrast, the analysis for fracture-pressure decline, introduced by Mayerhofer et al., couples unsteady-state linear flow from the fracture with a varying skin effect at the fracture face, and superposes the leakoff history on the pressure decline. This guarantees a correct rate convolution to account for pressure-dependent fluid loss. The reservoir permeability, fracture-face resistance, and leakoff area can be determined. A comparison of the two methods and their relationship is presented in this paper, using real field cases (a deep and a shallow gas reservoir). The authors show that the use of modern well-testing log-log diagnostic plots to determine fracture closure pressure is superior to drawing a straight line on a G-function plot or a square-root-of-time plot.

Fluid Leakoff Delineation in High-Permeability Fracturing

Abstract: Starting from the original concept proposed by Carter, Howard and Fast, this paper reviews the description of fracturing fluid leakoff in view of modeling flow in porous media. It is shown how various linear leakoff models have been developed and why a new, radial leakoff concept is necessary for high-permeability fracturing, where the injection time is commensurable to the response time of the reservoir. Using Laplace space methods, the new radial leakoff law is calculated and compared to linear leakoff. For comparison purposes a calibration test executed in high-permeability formation is interpreted using several approaches, namely: linear leakoff1bulk leakoff coefficient; filtercake resistance1linear flow in the formation and finally, filtercake resistance1radial flow in the formation.

Technology Transfer Through Integrated Production Engineering Software

Abstract: As the hand-held calculator revolutionized the capabilities of engineers 20 years ago, the desk-top computer is revolutionizing technology transfer in engineering practice today. For example, more than 10,000 independent oil/gas producers in the U.S., most of whom have difficulty gaining access to the most updated technology, rely on personal computers to keep up with the explosion of information and engineering process developments. In almost all petroleum companies, technical staffs are becoming small, and often, one or a few engineers serve as geologists and reservoir, drilling, and production engineers. Their needs demand software that is up to date, easy to understand and use, and able to run on small computers. This paper presents an integrated production software system, that can assist a production engineer with the design of an optimal well production system and can be used as training and technology transfer aids. Based on the new book Petroleum Production Systems, the software focuses on production engineering diagnosis and design tasks in reservoir inflow performance and well deliverability, skin identification and calculation, multiphase flow in pipes, well testing analysis, hydraulic fracturing design, acidizing design and artificial life design. The latest models and correlations describing these processes are incorporated in the package.