Developments in Well Completion Techniques

Field experiments indicate that well stimulation efficiency can be increased by engineering the completion process as an interrelated series of steps. These steps can be selected in a manner tat will create conditions most conducive to successful stimulation. Revision of perforating procedure, and consideration of injection rate per hole as a basis for designing fracture treatments will aid in successfully completing wells at lower cost. Pressure behavior patterns can be translated into efficiency which in turn can be indicative of the effectiveness of the treatment. Introduction The method of treating wells to increase production has not changed greatly through the years. Acid, and most recently, fracture fluid, have been injected into the formation with no real attempt being made to engineer the treatment. Injection rates, volumes, and perforating procedures have been selected on past experience or "rule of thumb" type thinking. In an attempt to improve the effectiveness of well stimulation methods, several innovations have been employed. Perforating procedure has been revised to reduce the number of holes shot. This is accomplished by reducing perforation density (no. of holes/ft) and by being increasingly selective in the placement of the perforations. The use of a value called injection rate/hole as a primary factor in designing stimulation treatments has increased the effectiveness of these treatments. The analysis of pressure behavior during a treatment has revealed a method of recognizing the occurrence of communication behind the pipe. This in turn led to the development of a means of predicting the effectiveness of a treatment. This paper is concerned with the completion of wells which require stimulation to increase production. The methods described herein can be applied to any treatment which depends upon the injection of fluid into the formation. Developments There are three basic phases of well stimulation which have been revised as a result of successful field experiments. They are: hydraulic fracturing methods, perforating procedure, and the evaluation of the completion procedure. Taken individually, each is important; together, they represent a method of increasing the efficiency of present well completion techniques. Fracturing Since the inception of hydraulic fracturing as a means of increasing oil production, the oil industry has been constantly seeking to improve the techniques. The volume of treating fluids has risen, injection rates have climbed steadily upward, and blocking agents have been developed. The treatments were designed principally by rule of thumb or by past experience.