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Retired DACC IRP Volume #06 - Critical Sour Underbalanced Drilling

Critical Sour Underbalanced Drilling Industry Recommended Practice (IRP) applies to the underbalanced drilling of critical sour wells. NOTE: As of October 2023 IRP 6 has been ‘Retired’. This IRP no longer reflects current best practices and will not be updated or maintained. The information remains posted and available for historical reference.
January 28, 2004

This Industry Recommended Practice (IRP) applies to the underbalanced drilling of critical sour wells.

The well control equipment IRPs were developed with the consideration that the hydrostatic head of the drilling fluid column no longer is the primary method of well control. The well control equipment is the primary well control mechanism to prevent escape of sour well effluent and ensure the safety of on-site personnel during the critical underbalanced drilling operations. The guidelines were developed with two lines of defense for all operations.

The drill string recommendations were developed with regard for the issues and implications of maintaining the integrity of jointed tubulars or coiled tubulars when exposed to sour effluent flow during a critical sour underbalanced drilling operation, and includes consideration of pressure integrity of all surface related components.

The surface circulating equipment includes all equipment downstream of the BOP stack that is necessary for the safe circulation, separation and handling of sour effluent flow from wellbore. The recommendations were developed with consideration for pressure, material specifications, erosion, corrosion, fluid and solids handling.

Wellbore integrity recommendations were based on the issues and implications of sour effluent flow in the wellbore such as: casing metallurgy, wear and corrosion and cement, open hole and wellhead integrity.

The circulating media IRPs were developed recognizing the importance of the circulating media in sour underbalanced drilling and considered media properties, kill fluids, corrosion, monitoring, handling, storage, trucking and waste disposal.

Safety recommendations for on-site personnel were intended to enhance existing regulations and industry standards recognizing the added safety concerns involved in sour underbalanced drilling.

Wellsite supervision recommendations are intended to complement existing IRPs, industry standards and regulatory requirements, particularly regarding the qualifications of personnel, level of supervision, and training.

Developer: DACC
Sponsor Organization: CAPP
Current Status: Retired October 2023
Other Information: For historical reference only