Paper: Update On Drainhole Drilling Empire ABO

ARC0 Oil and Gas Company has completed six drainhole wells in the Empire Abo Unit and plans to complete four more in early 1984. A drainhole well is one in which the wellbore has been deviated from vertical to horizontal with a turn radius of 20 to 30 ft. The horizontal hole extends up to 200 ft. Figure 1 illustrates an ideal drainhole completion. The increased surface area open to flow in the oil column reduces the susceptibility to gas coning as compared to conventionally completed wells. "Conventional Well" refers to a cased, vertical wellbore which has been perforated and acidized, (Fig. 2). A density-controlled acid job is generally used when stimulating to prevent etching upward to the gas cap. Even with the density-controlled method, significant upward etching occurs, increasing the susceptibility to gas coning. Initially, new wellbores were drilled for the drainhole completions. Recently a technique was devised and tested in the field to complete existing cased wellbores as drainhole wells. The main advantage of this new procedure is a substantial saving in drilling and completion costs. This paper summarizes the observed performance of the drainhole wells. A basic outline of the procedures used to drill the first six drainhole wells is included.