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.

Introduction

Lone Star Producing Company, Dallas, has set a new depth record, 31,441 feet, on their Bertha Rogers #1, near Burns Flat, Oklahoma. The old record, also held by Lone Star, is 30,050 feet, set on their #1 E. D. Baden in the same general area of Oklahoma.

Since these wells are the first ever to exceed 30,000 feet, they are the trend setters as the industry is forced to probe deeper for hydrocarbon deposits and/or geothermal energy. The knowledge and experience gained on these wells should prove invaluable in the planning of future deep tests.

This paper deals with one facit of the latest well, the drilling fluids. Included is a brief description of the geological characteristics that were expected in this well, a summary of the mud types and problems encountered while drilling, and some discussion of the auxiliary equipment and testing programs that are necessary for maintaining an optimum fluid at all times. It is hoped that from all this, the reader will gain some insight into the details concerned in handling a job of this magnitude, and possibly use this information as an aid possibly use this information as an aid for improvement in the future.

EXPECTED GEOLOGY

As is the case for most wells, the expected geological characteristics for the Rogers were determined from seismic data and offset well information in the same general area. Because of the depth, however, the bottom portion of the well could be classified as a rank wildcat, with the characteristics highly speculative.

The Burns Flat area of Oklahoma overlies part of the Southern flank of the Anadarko Basin. This flank is a steep, block faulted limb, paralleling the Amarillo-Wichita uplift (Fig. 1). The "Anticipated Geological Section" (Fig. 2) gives a better idea of the formations to be penetrated.

The primary target for this well was the Devonian dolomite (Hunton), which was non-commercial in the Baden test.

The sediments of the Anadarko basin are mainly carbonates with mixed layers of sand and shale. However, because of the intense folding, faulting, and uplifting that has taken place along the southern flank of this basin, massive sections of shale and some sand are predominant from about 12,500 feet to in predominant from about 12,500 feet to in excess of 23,000 feet.

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