American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.
Discussion of this paper is invited. Three copies of any discussion should be sent to the Society of Petroleum Engineers office. Such discussions may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.
The Delaware Basin of West Texas and the Anadarko Basin of Western Oklahoma and the Texas Panhandle are currently the most active areas in the United States insofar as development of ultra deep formations is concerned. Nearly all of these deep formations in both areas require stimulation to be commercially productive. While some of the formations in productive. While some of the formations in the two areas appear to respond similarly to laboratory tests, different stimulation treatments have evolved. Although fracture acidizing is common to both areas, the types and concentrations of acid and techniques of application vary greatly. Since effective stimulation is obtained in both areas, it was felt that a comparison of factors involved in treatment design, the treatments themselves, and the results obtained might lead to some common factors that would be useful in design of more economical and effective stimulation treatments for all ultra deep formations. This paper presents these comparisons for the Delaware and Anadarko Basins. An analysis of these comparisons attempts to explain the reason for variations in treatment design in some instances and to show why one type, or even a modification between the two, might be better in other instances. The paper also presents some of the basic considerations presents some of the basic considerations involved in stimulation of all ultra deep formations.
The Delaware Basin of West Texas (Fig. 1) and the Anadarko Basin of Western Oklahoma and the Texas Panhandle (Fig. 2) are both active in development of ultra-deep (18,000–25,000) formations. Target sands in the Delaware Basin may be the Wolfcamp, Morrow, Devonian, Frisselman or Ellenburger, while primary targets in the Anadarko Basin may be either the Morrow or Hunton. The deepest of the targets in each basin, the Ellenburger and the Hunton, are similar in many respects. Both are massive sections with narrow zones of porosity development. The Ellenburger is a highly soluble dolomite while the Hunton is an even more soluble limestone. The zones of porosity development in the Hunton, however, are dolomitic. Depths, bottom-hole temperatures, porosities and permeabilities of the two porosities and permeabilities of the two formations are roughly equivalent as shown in the generalized comparison in Table 1.