Webster, Kale, Member SPE-AIME

Abstract

This paper describes the current completion methods being used in "tight" or low permeability reservoirs of the Austin Chalk, Canyon Sand and Morrow Sand.

Formation damage has been a major consideration in all of these reservoirs and has strongly influenced the drilling mud, testing, cementing, perforating and stimulation. All of these factors influence the completion practices and are described for each reservoir. practices and are described for each reservoir. The Austin Chalk in the Pearsall Field is often described as producing from natural fractures. The method of finding these fractures includes coring, logging, and in some cases slant hole drilling through the pay section to intersect more of the fractures. Three basic fracturing fluids and methods have been used to treat the Austin Chalk and the average treatment now costs $35,000.

The Canyon Sands of Sutton and Ozona Counties, Texas are air or gas drilled. Most of the wells are fracture treated using the ball sealer multistage and gelled water technique or a gelled weak acid and limited entry. CO2 is used in many of the gelled acid treatments which include non-emulsifiers, iron stabilizers and KCL to prevent clay swelling.

Most of the Morrow Sand wells of eastern New Mexico are drilled with very low water loss muds, drill stem tested and then cemented with low water loss cement using KCL in the water to prevent cement filtrage damage to the formation. The most common method of perforating is through tubing with a differential into the wellbore. Some wells are completed natural but most respond to a small acid "clean-up" treatment. Data from a study of field results are included in the paper. Many of the completion problems paper. Many of the completion problems attributed to formation damage were due to poorly developed porosity and permeability poorly developed porosity and permeability often associated with edge wells. This means well cost could be substantially reduced by re-evaluating the mud, casing, tubing and stimulation programs.

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