Deep Sour Gas Drilling and Completion in South Aquitaine of France
Authors: Guiraudet B. 
Published: December 2007

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

This paper was prepared for the Deep Drilling and Production Symposium of the Society of Petroleum Engineers of AIME, to be held in Amarillo, Texas, Sept. 8–10, 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 in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in 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.

The search for deep sour gas reserves in the southwest of France along the Pyrenees Mountains introduced numerous problems while drilling at 20,000 ft with bottom-hole pressure of 16,000 psi. Present industry reserves already discovered in the same area are in the range of 10 Tcf, but existing fields are shallower (10 to 17 thousand ft) with less pressure (10,000 psi). pressure (10,000 psi).Five 20,000-ft wells have been aimed at the deeper reserves. Three Esso REP wells have been drilled and two found sour gas at high pressure. One well will be tested in the fall pressure. One well will be tested in the fall of 1974 for a long production period.

Significant efforts have been made on casing design and specifications, drilling fluids, and special procedures for H2S handling and emergency planning. Completion design provides for safety and the ability to control provides for safety and the ability to control the H2S effects on tubulars.

Present experience indicates that the evaluation of deep sour gas prospect at high pressure can be done safely with reliable pressure can be done safely with reliable tubular goods and a great emphasis on the personnel educational phases of blowout training personnel educational phases of blowout training and prevention.

Introduction

For the last 5 years, the southern part of the Aquitaine Basin along the Pyrenees Mountains has been one of the main targets for Esso REP exploration. Here, sour gas prospects are present at 20,000 ft with bottom pressure of present at 20,000 ft with bottom pressure of 16,000 psi which creates numerous problems. Industry reserves already discovered in the same area are in the range of 10 Tcf, but existing fields are shallower (10 to 17 thousand ft) with lower pressure (10,000 psi).

Fig. 1 shows the location of SNPA-operated sour gas fields of Lacq and Meillon, and of some other smaller fields. Total reserves amount to 10 Tcf. Current rate of production is about 1 Bcf/D. In the Lacq field, the pay is at 12,000 ft, the BHP is 9,000 psi, and the H2S content is 15 percent.

Exploration prospects are shown at Berenx, Came, Hasparren, and Lannemezan. The Came and Hasparren wildcats were drilled in 1972 and were dry. Two wells were drilled on the Berenx structure by Esso REP in 1969 and 1973 and found sour gas at high pressure. No production tests were run, but Berenx Well 2 will be tested in late 1974. The Lannemezan structure was al drilled in 1972, found sour gas at normal pressure at 20,000 ft, and a second well was pressure at 20,000 ft, and a second well was spudded by our partner in Dec. 1973.