The Deep Smackover Formation - A Challenge To Wireline Operations
Authors: Hayes Donald A. 
Published: December 2007

Because of the presence of hydrogen-sulfide gas, cased-hole wireline operations in the deep Smackover formation of northwest Florida require special measures for the protection of personnel and for the maintenance and successful operation of equipment. This paper describes the problem and reports results that have been achieved. Examples of spinner Flowmeter surveys and Gradiomanometer, Temperature, and Thermal-Decay-Time logs are shown to illustrate some of the cased-hole operations that can be successfully performed on a routine basis in the hostile hydrogen-sulfide environment.

Introduction

The Smackover formation is productive in several established oil and gas fields in Northwest Florida. Three of the oil-producing fields are: Jay-Little Escambia Creek (Jay-LEC), Blackjack Creek, and Finnie Church. The Big Escambia Creek and Flomation fields are gas productive. Produced hydrogen-sulfide-gas concentrations vary from 10 to 20 mol percent throughout these fields.

Several of the examples to be shown in this paper are from the Jay-LEC field. In this field, Exxon Company, U.S.A., instituted in the Spring of 1974 a logging program utilizing the Schlumberger Full-downhole flow profiles. Later, Thermal-Decay-Time logs, perforating, and Temperature surveys were included. The oil produced from these wells is a sour crude (10 mol percent H2S). Bottom-hole temperature in the producing wells is about 285F and bottom-hole pressure is about 5,100 psi. These conditions along with the presence of hydrogen-sulfide gas present formidable operational and maintenance problems for successful wireline operations. problems for successful wireline operations. Careful attention to the safety of personnel, when exposed to the presence of hydrogen-sulfide gas, is mandatory. Indoctrination of crew members on the use of air-breathing apparatus and wellsite-safety procedures are required. procedures are required. Maintenance of the surface pressure-control equipment, logging cable, and downhole equipment is essential. Surface pressure-control equipment must be tested at the wellsite after rigging up. Logging cable must be inspected after each operation. Downhole tools are subjected to a careful maintenance program. program. Wireline operations involving concentrations of hydrogen-sulfide gas call for planning on the part of both the logging company and the lease operator. Attention to detail, from the initial contact (when job planning begins) to execution of specific safety procedures at the wellsite, leads to success. procedures at the wellsite, leads to success. Safety and maintenance programs have been developed which makes it possible to achieve wireline services such as Production Logging, Gamma-Ray logging, perforating, and Thermal-Decay-Time logging. Several perforating, and Thermal-Decay-Time logging. Several field examples are presented which illustrate the results that can be obtained from wells containing H2S gas and how such results can be useful in producing the wells.

PERSONNEL SAFETY PERSONNEL SAFETY Logging-crew members should be made aware of the physiological effects of hydrogen-sulfide gas. This physiological effects of hydrogen-sulfide gas. This can be accomplished through a continual educational process. Indoctrination of new crewmen and reminders process. Indoctrination of new crewmen and reminders to the older ones of the danger involved will guard their safety for operations in an H2S environment.

Hydrogen sulfide is a colorless gas and is highly explosive in mixtures with air in concentrations of 5 to 27 mol percent (for gas mixtures, approximately equal to percent by volume).