Search

Several models have been introduced for the characterization of multilayer reservoirs. However, some have failed to provide results when the skin factor of the layers is negative. Therefore, in this work, a model applying the concept of the maximum effective hole diameter has been used to simulate pressure tests in multilayer reservoirs. The pressure behavior of such systems is similar to that of naturally fractured double porosity reservoirs. Then, using the unique features of the log–log plot of pressure and pressure derivative versus time, some expressions have been developed to characterize the reservoir. The equations are satisfactorily tested on three field examples.

Flow behind the casing has normally been identified and quantified using production logging tools. Very few applications of pressure transient analysis, which is much cheaper, have been devoted to determining compromised cemented zones. In this work, a methodology for a well test interpretation for determining conductivity behind the casing is developed. It provided good results with synthetic examples.

The naturally fractured reservoir characterization is crucial because it can help to predict the flow pattern of fluids, and the storativity ratio of the fractures and to understand whether two or more wells have communication, among others. This paper presents a practical methodology for interpreting interference tests in naturally fractured reservoirs using characteristic points found on the pressure derivative curve. These kinds of tests describe a system that consists of a producing well and an observation well separated by a distance (r). Using characteristic points and features found on the pressure and pressure derivative log-log plot, Analytical expressions were developed from the characteristic points of the pressure and pressure derivative log-log plot to determine the interporosity flow parameter (λ) and the storativity ratio of the fractures (ω). Finally, examples are used to successfully verify the expressions developed so that the naturally-fractured parameters were reproduced with good accuracy.

Well testing is the cheapest and most accurate tool available to find the distance from a well to a linear constant-pressure boundary or fault. Several methods exist in the literature with which to determine this parameter. Most of them use conventional analysis and are only useful for isotropic reservoir systems. The few methods for anisotropic systems obtain the well-to-discontinuity distance through conventional analysis, type-curve matching and TDS technique, and then a correction by anisotropic effects is applied. In this work, a unified behavior of the pressure derivative was found, so the new shorter and most practical expressions used to find the distance from the well to the discontinuity, including the simultaneous effects of anisotropy angle and anisotropy index, are included. These new formulae were successfully tested with two synthetic examples and one field case example, and deviation errors higher than 30% are observed if an anisotropic system is treated as an isotropic one.

Often, interpretation of interference tests is performed for systems acting under radial flow regimen conditions by means of conventional straight-line method, type-curve matching and TDS technique. For linear and spherical flow cases, the interpretation of interference tests is performed by the conventional analysis and type-curve matching. These procedures do not allow verification of the estimated parameters; therefore, this paper presents the formulation of a more practical, useful and accurate methodology which is achieved based upon the determination of characteristic features found on the pressure and pressure derivative versus time log-log plot with the purpose of developing analytical expressions for the interpretation of interference tests under spherical and linear flow conditions. These equations were successfully verified by their application on synthetic tests.

Es común en la industria petrolera completar los pozos en forma selectiva. Incluso, dicha selección se efectúa de forma natural ya que la heterogeneidad del yacimiento podría causar comportamiento segmentado del pozo. La segmentación podría estar parcialmente abierto al flujo en virtud a la alto factor de daño bajas vetas de permeabilidad. Ellas pueden tratarse como una distribución no uniforme del factor de daño. Algunos pocos modelos se han introducido para capturar estos detalles especiales. Las metodologías de interpretación existentes usan análisis de regresión no lineal y la técnica TDS; pero, se adolece de ecuaciones para el método convencional. En este estudio se desarrolla la metodología convencional para la interpretación de pruebas de presión en pozos horizontales con zonas aisladas de modo que se puedan estimar las permeabilidades y los factores de daño. Las expresiones desarrolladas se probaron satisfactoriamente con varios problemas encontrados en la literatura y se compararon con los resultados procedentes de otras fuentes.

El flujo lineal es un régimen de flujo muy importante que se presenta en pozos fracturados, horizontales y yacimientos alargados. Tanto el análisis de pruebas de presión como de transitorio de caudal podrán verse afectados por la presencia del flujo lineal. Para el caso de producción a caudal variable, la mayor parte del análisis se realiza mediante ajuste de curvas de declinación y poca atención ha recibido el análisis transitorio de caudal. Este artículo presenta las ecuaciones gobernantes usadas para análisis transitorio de caudal en sistemas alargados y proporciona ejemplos mediante el método convencional. La metodología permite la estimación de la permeabilidad, el ancho del yacimiento y los factores de daño geométricos. Si la prueba es lo suficientemente larga se puede estimar el área de drenaje del yacimiento y la posición del pozo dentro del mismo. La metodología se verificó satisfactoriamente mediante su aplicación a pruebas sintéticas.