Chemical Systems for Water and Gas Control: Terminology, Evaluation Methods, Candidate Selection, and Expectations

Abstract

Because water and gas production often causes reservoir, wellbore, and surface facility problems, controlling water and gas production is a primary concern for hydrocarbon producers. Problems associated with water and gas production have triggered many companies, research institutions, and universities to study water- and gas-production problems and develop chemicals and mechanical products that can control these problems. Because of the varieties of studies and products there are differences in terminology regarding these chemicals and areas of application. As a consequence, there are differences in expectations of these products, too. In this paper, chemical systems are categorized as nonsealing and sealing. A standard testing procedure is suggested to help evaluate the performance of the different systems. Standardized testing should help the industry compare the performance of different systems under specific conditions. This paper will consider treatment techniques and operations to emphasize the importance of detailed job design and operations planning. The paper ends with a summary of the economics involved in water and gas production. The method presented for determining a treatment's value can be used to evaluate the feasibility of water- or gas-control treatments. Introduction Many problems that are associated with the production of unwanted water and gas can be solved by a mechanical and/or a chemical solution. When more than one method is available to solve a problem, a particular method's reliability, pricing, and convenience, as well as the experience of the user can determine the method of choice. Choosing the most suitable solution requires determining the cause of the water- or gas-production problem. Sometimes the production problems are present on reservoir scale. In other cases, the problem is caused by wellbore conditions, or the capacity of the surface-production installation may demand a water- or gas-control treatment. When the problem has been clearly identified, a suitable solution can usually be chosen. Understanding which system is suitable for an application can be confusing because of the many systems and chemicals available. Differences in terminology and interpretations of the performance of certain chemicals can add to the confusion. Laboratory testing that compares the performance of systems can help identify the most suitable chemical solution for a particular situation. A single experimental program should be used for directly comparing systems. However, McPhee1 has shown that the results of institutions with identical testing programs can vary even in relatively simple experiments. Therefore, in this paper, a standard evaluation method for water- and gas-control chemicals is proposed. Although a chemical may perform well under reservoir conditions in a laboratory test, a successful performance during an operation cannot be guaranteed. A primary reason for the relatively low rate of success in water and gas shutoff operations is the use of an incorrect candidate-selection process. Several authors have suggested procedures and guidelines for water- and gas-control interventions.2–5 In this paper, guidelines will be presented that can help improve the success rate of water- and gas-control operations. Justifying the expense of water- and gas-control operations requires knowledge of the financial goals of the treatment. The costs of the operation should be in balance with the benefits and risks. Because financial aspects are the drivers behind water and gas control, this paper will present guidelines for financial consideration.

Polymer Systems for Water Shutoff and Profile Modification: A Review Over the Last Decade

“…This technology uses a flowable mixture of polymer, crosslinker, and water. This process is referred to as the disproportionate permeability-reduction effect (Liang et al 1993(Liang et al , 1995Botermans et al 2001;Stavland et al 2006). Then, with time and temperature, it forms a physical barrier hindering water production.…”

A New Strategy for Pre-Selecting Gas Wells for the Water Shut-Off Treatment Based on Geological Integrated Data

“…Many authors [1,5,12,[41][42][43][44] agree that one of the most important criteria for assessing wells is the interpretation of the history of changes in the water ratio and its derivative, leading to the identification of the well water breakthrough mechanism. Correct identification of the water breakthrough mechanism allows the rejection of those wells which do not qualify for any chemical water shut-off treatment.…”