Optimization of Gas Condensate Reservoir Development by Coupling Reservoir Modeling and Hydraulic Fracturing Design

Abstract

Abstract This paper presents the results of a study that included both compositional reservoir simulation and hydraulic fracture modeling. These models were used to optimize the production and recovery from a rich gas condensate reservoir. The study illustrates the upside potential of creating propped hydraulic fractures in a gas condensate reservoir. The reservoir is a multi-layered, low permeability, rich gas condensate formation. We performed this study to investigate the possibility of enhancing productivity from the reservoir and to increase gas recovery. Several wells existed in the field before the fracture treatment campaign was initiated. In this paper, we highlight modeling of three types of wells: vertical wells, vertical wells with multiple fractures, and horizontal wells. In all cases, the effect of condensate dropout around the well and/or the fracture is investigated. The effect of improving the relative permeability due to high velocity around wells is also discussed. The successful integration of reservoir and fracture modeling resulted in 40% cost savings when compared to the original development plan. Introduction The field we studied is located in North Africa. The field is a deep gas condensate reservoir. The reservoir trap is mainly stratigraphic with heterogeneous sand-shale sequences. On a macroscopic level, the reservoir is a low permeability thick sandstone, that contains a thin high permeability sand streak. Several wells were drilled to delineate and develop the reservoir for production. All wells encountered the tight sands in the field. The high permeability sand streak varied from the top portion of the reservoir to the bottom. The initial plan was to develop the field using 23 wells to achieve the required production levels as per the daily contracted quantity (DCQ). This paper illustrates the study that was carried to optimize the field production and the field applications that resulted in achieving the target production with drilling only 13 wells and hydraulic fracturing those wells. This resulted in a tremendous savings of around 42% from the project AFE while achieving the production target. In this paper we will concentrate on the reservoir simulation work for 3 of the key wells in the field. The reservoir sand contains rich gas-condensate with condensate yield of around 160 bbl/MMscf. The main objective of this work was to optimize the production from the development wells, and to maintain the production plateau for the longest time period, so we could deliver the gas to the sales pipeline at the contracted amounts. Our approach hinged upon coupling a compositional reservoir simulator with a rock mechanics hydraulic fracture model to predict and optimize the production plateau. The coupled model was used in reservoir development planning to maintain the gas production at the desired plateau required by the pipeline.