Material Certification Of Oilfield Well Control Equipment For Critical Sour Service Applications
Authors: Pizzey Talman B. 
Published: March 2010

Metallic components used in sour environments are susceptible to failure from sulphide stress cracking (SSC). Material recommendations and restrictions are intended to reduce the risk of ssc. The Blowout Prevention Review Committee (BPRC) formulated a series of documents entitled Alberta Recommended Practices (ARP). ARP contains very specific guidelines for well control equipment for drilling critical sour wells. Attempts to certify these components have found some items of non-conformance and significant problems with required documentation. One operator in an attempt to detail and assist the drilling contractor and rental companies is preparing a specification to outline their requirements for acceptable documentation and testing methods in order to qualify equipment for critical sour gas work. This specification, which encompasses the ARP requirements, offers a practical approach to certification and testing of well control equipment inc/riding BOP stacks, manifolds, valves and piping. The requirements of ARP as well as, the critical sour well control equipment specification will be presented.

Introduction

NACE Standard MR-01–75 "Sulphide Stress Cracking Resistant Metallic Materials for Oil Field Equipment"(l) provides a list of materials at hardness levels that are considered resistant to sulphide stress cracking (SSC) in pressurized H2S bearing environments. Under direction from the Blowout Prevention Review Committee (BPRC), an additional document entitled the Alberta Recommended Practices (ARP)(2), was developed to complement existing standards and specifications by providing greater detail to Alberta's drilling industry. The ARP exclusively addresses critical sour wells as defined by the ERCB Interim Directive ID 87–2, "Sour Well Licensing and Drilling Requirements".

The ARP document outlines an excellent approach towards achieving provincial-wide quality control for drilling critical sour wells. The next step is to heighten industry awareness of the recommendations. Because ARP currently has no legislative backing, enforcement is typically left up to the operators. Over the next few years, many of the operators will include these recommendations in proprietary specifications thereby substituting the word recommended with required. Conformance would often be assured by an audit of the equipment and documentation.

Unfortunately, enforcement of these recommendations can be particularly onerous to the drilling contractors and equipment rental companies. There is a definite time and cost barrier to overcome with respect to certification of existing equipment, however new equipment can be purchased with sufficient documentation to ensure conformance. The purchaser must specify what documentation is required (mill certificates, weld procedures, inspection reports), otherwise the documents will not arrive with the equipment. Maintaining complete certification also requires traceable record keeping. Naturally drilling contractors and rental companies with suitable documentation in place will be in the best position to offer a competitive bid.

The cost and effort required to certify existing equipment can be somewhat alleviated by proper record keeping and a better understanding of what is actually required. Often effort is expended in one direction while more severe problems remain unattended. For instance, repetitive testing could be eliminated by proper record keeping. Another problem is the use of inappropriate testing equipment due to a lack of awareness with respect to accuracy and limitations.

During audits of equipment documentation, many deficiencies and problem areas have been noted. A