Title : Permeability reduction threats and the opportunity to enhance well productivity in geothermal tight sandstone reservoir
Abstract:
Reservoir permeability is a lifeline of hydrocarbon in a reservoir in which fluid travels through to wellbore. Hence, any changes in nearby wellbore formation permeability will be tangible through oil rate at surface. If this effective permeability changed negatively, a reduction in oil rate will occur and will not be desired by any company. A drastic reduction in well productivity has been noticed in 6J-Area (tight sandstone reservoir). This reduction in permeability is due to mechanical and chemical formation damage mechanisms. In literature, those mechanisms are documented but still not well understood. 6J-Area Nubian reservoir has limited in-situ permeability, rock composition and high temperature which make reservoir formation too sensitive to foreign fluids and fluid velocity2 in wellbore vicinity and consequently, caused severe formation damage in about fifty percent of the total producible wells. The production loss range was between twenty to eighty percent of the well potential, therefore, the operator company had decided face the challenge and put an end to the permeability reduction since then this issue's being investigated and several laboratory tests have been performed to date. They indicated that fines migration, phase trapping effects, electrical stability and wettability alteration phenomena are the most likely reasons behind permeability decline. Avoiding the abovementioned formation damage requires more laboratory work which is still under investigation in order to economically optimize the introduced foreign fluid specifications and critical fluid velocity. Therefore, the focus was redirected to economically test the available technologies to restore or enhance well productivity in an oil well in 6J-Area. The objective of this paper is to illustrate conclusive results from a study aimed at incorporating the findings from best approach that have been operationally tested to remedy near wellbore damage created by any of the damaging mechanism. The successful tested treatment was applied on other wells in which the well productivity not only restored but also enhanced to nine-fold increase. The best effective method will be utilized for full field implementations.
