--> ABSTRACT: Simulating Geochemical Formation Damage Using REACTRAN Computer Code, by Craig H. Moore and P. Ortoleva; #91030 (2010)

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Simulating Geochemical Formation Damage Using REACTRAN Computer Code

Craig H. Moore, P. Ortoleva

Local reduction of reservoir permeability resulting in attenuated production levels can be caused by chemical reactions between completion fluids and reservoir rocks. Predictive capability for determining the probability and extent of this formation damage could significantly reduce the amount of lost production/revenue incurred in this manner.

The geochemical system created during completion is a coupled flow/reaction, nonequilibrium system that can be realistically modeled by the computer code REACTRAN. To demonstrate this, simulations of formation damage to an offshore well in the Gulf of Mexico are presented. The actual well showed good flow rates prior to completion, but, after having been shut in for 18 months, the CaBr2 completion fluid had all been displaced to the reservoir and the flow had decreased so much that the well had to be abandoned. Simulations using REACTRAN show that, under the conditions of flow, temperature, and composition that existed at this well, precipitation of secondary silicate minerals can result in a porosity change from 10 to 2% in the period of a year. This porosity reduction cou d easily result in the drastic flow attenuation observed in the well. Results of simulations of other, hypothetical wells completed under different physicochemical conditions are presented and the effect of these environments on the extent of formation damage is discussed. Because different well environments are more or less prone to geochemical formation damage, and because of the different types of processes that occur, a code like REACTRAN is essential for the simulations.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.