Hydrogen Sulfide In The Drilling Industry

Abstract

Carter, D.R., and Adams, N.J., Prentice and Records Enterprises, Inc. Prentice and Records Enterprises, Inc. Copyright 1979, American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Petroleum Engineers, Inc. This paper was presented at the 1979 Society of Petroleum Engineers of AIME Deep Drilling and Production Symposium held in Amarillo, Texas, April 1–3, 1979. The material is subject to correction by the author. Permission to copy is restricted to an abstract of not more than 300 words. Abstract When a well is to be drilled in a known or suspected sour gas area a number of precautions must be taken. These measures can be separated into the three general categories of (1) methods of protecting the rig and site personnel, (2) safeguards to protect the general public, and (3) precautions to safeguard all equipment from exposure to hydrogen sulfide. Introduction Hydrogen sulfide (H2S) has become an important topic in recent years due to the increasing demand for hydrocarbon products. To meet these demands, operators are now increasing drilling activities in known sour gas areas. In addition, sour gas has been reported in old fields where the presence of hydrogen sulfide had not been previously reported. To drill and complete a sour gas well safely and at minimum costs, operators need a basic understanding of the effects of encountering hydrogen sulfide. Hydrogen sulfide is a toxic gas that can cause sudden death from exposure to low concentrations of the substance. In addition to the toxicity, hydrogen sulfide is very corrosive. H2S corrosion adds tremendous costs to an already expensive endeavor if the operator has not taken proper precautions to prevent such damage. prevent such damage. This state-of-the-art paper presents pertinent topics relative to hydrogen sulfide drilling such as the responsibilities imposed by federal and state regulations. Emphasis is placed on OSHA and NIOSH rules and state regulations. The effects of hydrogen sulfide on the rig site worker and equipment also will be presented as well as methods for preparing and protecting workers and equipment for exposure to an H2S environment. RULES AND REGULATIONS The operator is faced with many rules, regulations, and standards when attempting to drill and produce hydrocarbon products containing hydrogen produce hydrocarbon products containing hydrogen sulfide components. The regulatory agencies are found both on the state and federal level. The primary regulations will be presented in the following primary regulations will be presented in the following section while details of these regulations can be found in the referenced sources. Occupational Safety and Health Administration (OSHA). Although a particular drilling area may be void of state regulations relative to hydrogen sulfide drilling, many federal regulations and standards must be followed anytime a toxic environment is encounterd. The Office of Occupational Safety and Health Administration (OSHA) in its 29 CFR 1910, Subpart I 1910.134 states that "(1) In the control of those occupational diseases caused by breathing air contaminated with harmful dusts, fogs, fumes, mists, gases, smokes, sprays, or vapors, the primary objective shall be to prevent atmospheric contamination. When effective engineering controls are not feasible, or while they are being installed, appropriate respirators shall be worn pursuant to the following requirements. (2) Respirators shall be provided by the employer when such equipment is necessary to protect the health of the employee. The employer shall provide the respirators which are applicable and suitable for the purpose intended. The employer shall be responsible for the establishment and maintenance of a respiratory program."In this same publication, guidelines are presented for the selection of respiratory equipment presented for the selection of respiratory equipment on the basis of exposure. The standard from which the information is obtained is ANSI Z88.2. This standard classifies H2S as an extremely toxic gas and is immediately dangerous to health. Those respirators which are acceptable must be of the positive pressure type which maintains a constant positive pressure type which maintains a constant pressure within the facepiece at all times. This pressure within the facepiece at all times. This classification is further defined by 29 CFR 11 which specifically states the types of respirators that are approved in an H2S environment. (See Table 1)American National Standards Institute (ANSI). Another national standard which has a great impact upon respiratory equipment is American National Standards Institute Z37.2-1972.

Improvement of Hydrogen Sulfide Scavenging via the Addition of Monoethanolamine to Water-Based Drilling Fluids

“…The lower pH of SourScav compared to the higher pH of both triazine and MEA is attributed to the significant pH change induced by the scavengers. Generally, the practical pH range of water-based drilling muds is in the range of 9.0–11.0; however, increasing the mud pH value above this range is a recommended practice to limit the H 2 S effects, and the regulations set pH level of 10 to be always maintained as a minimum in a sour environment . Accordingly, the pH resulting from the use of the MEA complies with the regulations and recommendations.…”

Experimental Investigation of Using Manganese Monoxide as a Hydrogen Sulfide Scavenger for Aqueous Drilling Fluids

“…In general, the pH range for aqueous muds is typically between 9.0 and 11.0, while in the presence of H 2 S, it is recommended to maintain a higher pH level in order to lessen its acidifying effect . Also, the regulations for drilling in sour environments mandate a minimum pH level of 10 . Based on these requirements, the pH achieved by the MnO-containing fluid is in compliance with these regulations, while using SourScav raises a concern and necessitates more consideration for alkalinity control.…”

“… 13 Also, the regulations for drilling in sour environments mandate a minimum pH level of 10. 50 Based on these requirements, the pH achieved by the MnO-containing fluid is in compliance with these regulations, while using SourScav raises a concern and necessitates more consideration for alkalinity control.…”

Investigation of Using Various Quantities of Steelmaking Waste for Scavenging Hydrogen Sulfide in Drilling Fluids

“…On the other hand, the addition of 1, 2, and 3 g steelmaking waste to the base mud reduced its pH to 10.4, 9.8, and 8.5, respectively. In general, the acceptable pH range of water-based drilling fluids is in the range 9.0-11.0; yet, maintaining a pH value greater than 10 is required when drilling H 2 S-bearing formations [84]. As a result, the pH of SWM1 passes the pH criterion, SWM2 is near to the threshold limit of 10, and SWM3 is less than this limit.…”