A Comprehensive Approach to Formation Damage Diagnosis and Corresponding Stimulation Type And Fluid Selection

Abstract

Abstract This paper describes a comprehensive approach to formation damage diagnosis. Once the cause of formation damage and the location of the damage is known, then one can select the optimum fluid and design the best treatment to remove the damage. Our approach combines the domain knowledge with the best available expertise, then uses new technologies, which include fuzzy logic and an expert system. Our approach first diagnoses the formation damage mechanism, then we determine the treatment method, and finally we select the optimal fluids for the treatment. Introduction The selection of treatment fluids for matrix stimulation is more complicated than for hydraulic fracturing. In matrix acidizing, we first have to determine the damage mechanism and the location of the damage; then, we can choose the proper treatment fluid based upon the damage type, lithology, bottomhole temperature, and formation permeability. Near wellbore formation damage can be caused by chemical or mechanical processes that occur in the formation very near the borehole. Formation damage resulting from drilling, completion, production, or stimulation treatments can substantially reduce the productivity or injectivity of a well. Different types of formation damage require different types of stimulation treatments to repair the damage and increase productivity. However. diagnosing formation damage is not a simple task. Diagnosing damage requires an adequate data set, careful analysis and experience. Multiple damage mechanisms may coexist, which makes the problem even more complicated. Many investigations have been conducted to learn how to diagnose formation damage. Numerous fluid systems and methods to remove formation damage have been developed. However, diagnosing the formation damage mechanism, then removing the damage from the formation or wellbore is a difficult problem. The problem becomes more difficult when adequate data are not available to properly define the problem. Two papers have been published that discuss how expert systems and rules can be used to assist in the analyses of formation damage problems; however, no complete approach to the problem of diagnosis, then treatment has been written. In this paper, we describe a complete approach to the problem. Applying an expert system and fuzzy logic techniques, we have develop a comprehensive approach and a computer model, that can be used to diagnose formation damage types. We also choose the optimal stimulation method and an optimal treatment fluid system to remove the damage. Our methods are especially useful when very little data are available and/or multiple damage mechanisms may coexist. The approach helps an engineer design the optimum matrix stimulation treatment. P. 811