This paper was prepared for the Permian Basin Oil Recovery Conference of the Society of Petroleum Engineers of AIME, to be held in Midland, Tex., March 11–12, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication is the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication is the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

Abstract

Attempts to stimulate marginal gas producers in Sutton County, Texas, has provided an producers in Sutton County, Texas, has provided an opportunity to evaluate several types of stimulation fluids on a comparative basis. The fluids used here included water base, oil base, and acid base fluids. A thorough study of the production history of wells following treatment production history of wells following treatment demonstrates the effectiveness of the different fluids on a long term basis. Conclusions drawn from this study provide a guide to selection of fracture fluids for tight gas sands.

Cost-performance factors are explored as they apply to stimulation of marginal gas production and further conclusions are drawn production and further conclusions are drawn concerning the importance of formation damage as a function of formation petrophysical properties. Examples are shown to indicate formation damage is a factor to consider in fracturing tight sands but performance compromises may be made in the choice of fluid to obtain maximum frac penetration. penetration

Introduction

Shortages of many chemicals used in well stimulation treatments has led to re-evaluation of many gas well treating techniques. Nowhere has this been more the case than in the Canyon play of Sutton County, Texas. A previous paper play of Sutton County, Texas. A previous paper (SPE 4678) describes the treating methods used in the initial development of the Sawyer Field. This study has been continued and cost effective fracturing has resulted. The results of the fracturing development may serve as a model for gas well stimulation in other areas with production from similar zones. production from similar zones.

FORMATION

The Canyon, a Pennsylvanian Age sand, is generally found at approximately 6500 feet and is produced to about 8200 feet. The zone is massive with many "ratty" sections. These sections are low in permeability (1 md) and porosity (8–12 per cent). When contacted by fresh water there is a noticeable clay migration. Acid response tests indicate migration damage accounts for about 35–40 per cent loss in permeability. Formation liquid saturation is low and any liquid entering the formation may cause further loss in relative permeability. Gas-oil ratios indicate an essentially dry gas formation.

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