Control of Water Production in Reservoirs with High Temperature Produced by Water Drive
Authors: Ventresca M.L. , Torres G. 
Published: December 2007

The evaluation of three commercial gelifying systems at 130 degrees C, in their efficiency to reduce, totally or selectively. The permeability of the porous medium to water o crudo has been studied. It was found that two of them may be applied in the strategy designed to control excessive water production in natural drive reservoirs located in the Southwest of Venezuela.

Introduction

Water control is a term applied to a family of processes designed to solve problems or defects in reservoirs. The water control processes reduce the excessive production of water and the loss in oil production as a production of water and the loss in oil production as a result of:Channels which make the water circulate from the injection well to the production well in the water injection processes.Irregular injection arrangements, which cause premature irruptions of water in the nearest production wells and,Water cones or tongues in situations of natural or artificial drive situations.

In this latter case, the ingress of water into the production wells is the consequence at the presence of an extensive water zone underlying the producing lenses, which, in turn comes into contact with the oil-bearing zone. When the well is placed in production, in the zone adjacent to it, the water-oil contact advances vertically forming water cones which result in a excessive production of water. When the quantity of water production of water. When the quantity of water produced is great, the pumping equipment can become produced is great, the pumping equipment can become incapable to maintain the flow required to avoid the forming of a significant column of fluid in the well. The resulting counter pressure may cause substantial decreases in the production of petroleum. In addition, when the water production zone occupies a great part of the well, the oil does not have any access and the reduction of the production becomes more evident even with the installation of greater capacity pumping equipment. Great volumes of water can also reduce the capacity of the surface equipment, causing limitations to the production. Various methods have been proposed to control the flow of fluids through the formation involving the modification of the in situ permeability. Of these methods, the most successful are those using polymers, usually polyacrylamides since they have the peculiarity of diminishing the permeability of the water in peculiarity of diminishing the permeability of the water in the well zone without significantly affecting the permeability to oil. This makes it unnecessary to isolate permeability to oil. This makes it unnecessary to isolate the water producing zone. The great part of the polymer will enter in said zone since generally it is the zone of the least resistance to the flow and whatever enters in the oil-producing zone will have little effect. In addition, after the treatment with polymers, the oil may again enter into the well through the zone which produced the water and which has been contacted by the polymer solution. In some cases, gels resulting from the reaction between polymers or other organic substances through metal ions are used. There is a variety of techniques for the formation and placement of the gels and these may affect or not the permeability to oil, for which reason it is important to know their behavior and the manner of placing them in the reservoir. placing them in the reservoir. Different commercial firms offer sealing and non-sealing polymeric and non-polymeric systems, understanding as non-sealing those which reduce the permeability to water and affect the crude to a lesser permeability to water and affect the crude to a lesser degree and, as sealing, those which reduce both permeabilities. permeabilities. These systems are characterized by two very important variables: their consistency and their gelification time. The consistency, because it indicates the nature of the gel with respect to its hardness, breakability, elasticity, etc., and the time of gelification, because as the gelification reaction is occurring, there is an increase in the viscosity value of the gelifying system up to the point that it becomes impossible to measure it.

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