Well Completions for Waterflood Operations

Abstract

Abstract Reservoir conditions in Permian sand fields of West Texas present problems in waterflood operations unique to that area. These are caused by upper water-bearing formations; a series of sand lenses in the producing zone separated by shale, sandy shale and dolomite stringers and gas sands above the producing oil zones. In some fields bottom-hole water is present in the down dip area in the principal oil-producing oil zones. pointed out that the most satisfactory methods used to overcome these problems could apply to any area where an open hole completion would be possible. The paper presents a discussion of current completion practices for injection and producing wells. The methods by which properly completed wells help to solve the problems of thief zones, injection rates, maintaining properly treated water, and isolation of the sands to be flooded are presented. A method for completion of cable tool holes, where the operator may chip core and shoot the producing zone before running casing is discussed in detail. Introduction The essence of water flooding is to inject water continuously into the pore spaces of an oil reservoir at a rate that will result in the production of the maximum amount of commercially recoverable oil. Any mechanical, chemical, or biological processes that assist or detract from this endeavor are of vital importance. In its simplest aspect the problem then resolves itself into injecting the most suitable water available into an oil bearing formation at the right pressure. This involves spacing, pattern, water treating and well completions. Pore spaces refer to any openings through which fluid could pass. The scope of this paper concerns itself with well completions. Injection well completion is the most critical factor to waterflooding success. This for the simple reason that the injection well is the sole medium for directing the water to its function. In like manner producing wells must be completed so that all waterflood oil can be produced. It is an economic waste to continually attempt to work over a completed injection well, and it is a hazard to try to solve all problems by increasing injection pressures.