Browsing by Autor "P. M. Adrian"

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Estimation of OGIP in a Water-Drive Gas Reservoir Coupling Dynamic Material Balance and Fetkovich Aquifer Model
(2018) S.. Zavaleta; P. M. Adrian; Michel Michel
Abstract Although various novel techniques were developed in reservoir engineering for estimation of hydrocarbons initially in place (HCIIP), conventional material balance still remains as one of the most reliable. Average reservoir pressure is critical input data for material balance, which is usually obtained by well shut-in. Nevertheless, this operation might be restricted due to economic and operational restrictions such as water production in gas wells. In contrast, daily production data is commonly available and can be used to calculate the HCIIP by applying any production data analysis techniques such as the Dynamic Material Balance (DMB) method. The application of such methods to volumetric gas reservoirs and naturally fractured reservoirs resulted in accurate and reliable estimations. However, for water drive gas reservoirs, where the water influx term should be introduced into the iterative process, research and field case applications are limited. This paper presents an extension to the DMB technique to water-drive gas reservoirs. A simultaneous estimation of the Original Gas-in-place (OGIP) and the water influx term is achieved by coupling the DMB technique with the Fetkovich aquifer model. Average reservoir pressure estimation can also be attained as a result of the coupled method. Results were validated by means of numerical simulation on a synthetic model and a field study case. Synthetic production data was generated by a commercial simulator and then analized with the coupled method. The calculated OGIP, water influx volumes and average reservoir pressure resulted comparable to simulator output as they presented a low relative error. Furthermore, application of the coupled method to the field study case yielded comparable results to those obtained by volumetric method.
Rate Transient Analysis in Two-Layered Reservoir Without Crossflow
(2021) Michael B. Vasquez; P. M. Adrian
Abstract Analysis of modern production data also known as Rate Transient Analysis (RTA) is a technique to perform reservoir characterization using the combination of bottomhole flowing pressure and flow rate data without the need to close wells. These methods allow the estimation of the Hydrocarbon Initially In-Place (HIIP), production forecast and main reservoir parameters. Several RTA methods have already been developed to analyze different reservoir models such as homogeneous, naturally fractured, geopressurized, hydraulically fractured, however, in the case of layered reservoirs the studies are almost null although there are several studies conducted in the area of pressure transient analysis. This paper presents the analytical derivation of the Palacio-Blasingame type curves to analyze production data of a two-layered reservoir model without crossflow or hydraulic communication between them. A new set of type curves were generated by applying the Gaver Stehfest algorithm with Matlab to achieve the solution of the inverse of the Laplace space considering a constant flow of production flow and a flow regime in the radial pseudosteady-state, then applying the definitions dimensionless the proposed method was derived. Synthetic data were generated with a commercial simulator to validate the method. Furthermore this paper presents a field case study application. The results were compared to the type curve for homogenous reservoirs, volumetric method as well as well testing results. Results confirmed the applicability of rate transient analysis technique in a two-layered reservoir without crossflow with a single drainage area and the same initial pressure for all layers (same pressure gradient of formation), and different values of thickness of the layers, permeability and porosity.