Pressure Data Analysis and Multilayer Modeling of A Gas-Condensate Reservoir

Abstract

Kailastila gas field located at Golapgonj, Sylhet, is one of the largest gas fields in Bangladesh. It produces a high amount of condensate along with natural gas. For the high values of GOR, it may be treated as a wet gas at reservoir condition. Three main sand reservoirs are confirmed in this field (upper, middle and lower). In this study, it has been shown that reservoir parameters of this gas field can be obtained for multilayered rectangular reservoir with formation cross-flow using pressure and their semi-log derivative on a set of dimensionless-type curve. The effects of the reservoir parameters such as permeability, skin, storage coefficient, and others such as reservoir areal extent and layering on the wellbore response and pressure are investigated. Shut-in pressures are used in calculating permeability, skin factor, average reservoir pressure, wellbore storage effect and other reservoir properties. The direction of the formation cross flow is determined, first by the layer permeability and later by the skin factor. Finally, it is recommended to perform diagnostic analysis along with multilayer modeling to extract better results. Reservoir can also be considered as a multilayer cylindrical and can also use these models for other fields.
Keywords: Pressure derivative analysis, Skin factor, Wellbore storage, Permeability, Multilayer