Evaluation of water production in tight gas sands in the Cotton Valley formation in the Caspiana, Elm Grove and Frierson fields

Abstract

Normally in tight gas sands, water production is not a problem but in such low permeability reservoirs it is difficult to produce gas at commercial flow rates. Since water is more viscous than gas, very little water is normally produced in low permeability reservoirs. The production of large volumes of water from tight gas sands, say 50-100 bbls of water per MMcf of gas constitutes a cause for concern. High water production (>200 bbls of water per MMcf of gas) has been observed in the low permeability Cotton Valley sands in the Caspiana, Elm Grove and Frierson fields of North Louisiana. This research evaluates water production in the above tight gas sands using field data provided by Matador Resource, a member of the Crisman Institute in Texas A&M university. The research is aimed at providing realistic reservoir scenarios of excess water production in tight gas sands. Log analysis, property trends and well production profiles have been used in establishing the different scenarios. The reservoir simulation results and the production trends show a possible water source from faults and fractures connecting the Travis Peak/Smackover sands to the Cotton Valley sands. An improved understanding of the reservoir would help in further field development.