Carbon Steel X65QS Pipeline Qualification for Extreme Sour Service a Global Approach: Line Pipe, Welding, Eca Methodology and Diyab Pipeline Case Study

In the wake of failures of large diameter pipelines made from plates using the Thermo-Mechanically Controlled Process (TMCP), the suitability of carbon steel material for sour environments where the H2S partial pressure is largely over 1 bar has been questioned. Understanding that seamless quench and tempered material are not prone to the same phenomenon as large diameter TMCP pipes, it has been decided to ensure the integrity of the DIYAB pipeline by qualification using the actual production environment pH=3.5 at 24°C and 6.84 bar H2S plus 6.84 bar CO2. The global approach includes the qualification to sour service resistance under 6.84bar H2S of the base material and the welds without post weld heat treatment. Fracture toughness tests under 6.84bar H2S were also conducted, and the results fed into an Engineering Criticality Assessment (ECA) to define the Non-Destructive Testing (NDT) acceptance criteria. The NDT tools were selected for their ability to detect the critical flaws and validated. The global approach methodology and results are presented.

Gaps in Material Qualification Requirement and Acceptance for Severe to Extreme Sour-Sweet Corrosive HPHT Environments Impacting Completion Design

Severe to extreme sour-corrosive environment assisted cracking (EAC) phenomenon are complex. Mandatory test qualification requirements and acceptance criteria is non-existent, in relevant API and NACE standards for fracture toughness of the CRA's. This paper, perhaps an industry first, attempts to highlight some of these gaps and how it translates into material strength uncertainties thereby impacting tubing design and risk assessment. The materials in this context are high strength group 1 to 4 corrosion resistant alloys of API 5CRA. Fracture toughness or critical stress intensity factor is a measure of resistance to failure due to crack propagation - a key parameter for HPHT tubing material selection and design. This material aspect of fracture toughness can be influenced by several factors like Microstructure, Strength, Hardness, Heat treatment, Anisotropy etc. Low temperature is generally considered as worst case, nevertheless at higher temperatures, well environment driven embrittlement can have a serious impact on the fracture toughness value. Therefore, with several factors influencing, its characterization is important to define the burst envelope of the tubing when exposed to severe to extreme sour-sweet corrosive environment typical of HPHT wells. A unique approach is followed to determine the brittle burst tri-axial envelope of selected tubing based on minimum fracture toughness value of the CRA material, referred to as KIMAT for SSC (or EAC) as prescribed by the mill. Proportional radial scaling is proposed to generate scaled down von-mises brittle-burst envelope. The tubing loads and the safety factors are analyzed to the shrunken envelope to visualize the risks of tubular failure under sour-sweet corrosive environment. The analysis includes varying crack depths of 5% and 3%. In addition, a minimum KIMAT for SSC (or EAC) value required to achieve full scale VME is investigated to determine specific material property requirements. TM0177 NACE D covers methods to measure fracture toughness KIMAT for sour service at ambient temperature only and does not address the context of EAC exposure at ambient or elevated conditions i.e., KIMAT for EAC.This implies that a methodology for evaluation of EAC risk is not available as yet. Guidance on the potential for corrosion to cause cracking of CRAs is given in Table B.1 of ISO 15156-3 with primary and secondary failure mechanisms. However, a quantitative test to cover the risk of cracking of materials by specifying minimum required KIMAT for EAC for each group type in 5CRA is non-existent. Even KIMAT for sour service minimum requirements with SSC as primary failure mechanism, e.g., group 1 CRA, does not currently exist. Consequently, KIMAT for EAC minimum requirements are considered as far-fetched. Additionally, mills prescribed KIMAT for SSC lacks basis due to gaps in the minimum fracture toughness requirement stipulations for group 1 to 4 CRA materials listed at API 5CRA. Therefore, this paper provides risk insights and potential of tubing failure that can lead to serious integrity issues on a HPHT well. A joint industry program or joint API/NACE task group is proposed as a logical next step.

Manufacturing of LSAW Pipes Using Hot Rolled Sheets for Sour-Service Application

The exploration and transportation of fluids from corrosive fields or reserves demand corrosion-resistant pipelines. The pipelines for sour-service application demand higher resistance to H2S corrosion because of higher sulphur content observed in the geographical locations. The pipelines laid in the corrosive and marshy lands demand high wall thickness to allow for wall thinning due to corrosion. The linepipes manufactured using TMCP plates are widely accepted for sour-service applications. The use of cut-to-length sheets from hot rolled coils for the manufacturing of LSAW pipes is economical but having limited acceptance by the pipeline operators. Welspun took an initiative to develop the linepipes for an onshore sour-service application using API 5L X60MS grade cut-to-length sheets from TMCP hot rolled coils procured from an approved steel mill. The LSAW pipes of 24” OD × 14.27 mm WT were manufactured by the JCO-E press at Welspun Pipes Mill in Anjar-Gujarat-India. The experience of 24”OD × 14.30 mm WT, API 5L X60MO grade pipes manufacturing using TMCP plates procured from another approved steel mill, was used to decide factors such as alloy design, cleanliness, strength, DWTT, hardness, HIC, SSCC, CVN for the selection of cut-to-length sheets. This paper deals with sheet-to-pipe behavioural changes in properties before and after cold mechanical expansion. Wherever possible, the comparison was also made with plate-pipe behavioural changes in properties.

Improved High-Pressure, High-Temperature (HPHT) Materials Qualification using Dissolved H₂S Concentration as the Sour Service Scalable Metric

Gas phase H<sub>2</sub>S partial pressure (P<sub>H2S</sub>) is associated with sulfide stress cracking (SSC) and is routinely used as the ‘scalable’ parameter to qualify materials for high-pressure, high-temperature (HPHT) wells. Candidate materials for HPHT wells routinely require ANSI/NACE MR0175/ISO 15156 compliance because a few mole ppm of H<sub>2</sub>S at high pressure may place the well beyond the 0.05 psia (0.3 kPa) sour service threshold. P<sub>H2S</sub> has been accepted historically as the scalable sour severity parameter. However, as the total pressure increases, the relationship between P<sub>H2S</sub> and the dissolved H<sub>2</sub>S concentration becomes non-linear. This limits the robustness of P<sub>H2S</sub> as the sour severity metric. Thus, ISO 15156-1:2020 now permits the use of H2S fugacity (f<sub>H2S</sub>), H<sub>2</sub>S activity (a<sub>H2S</sub>), and H<sub>2</sub>S aqueous concentration (C<sub>H2S</sub>) as alternatives for sour testing. This recent revision is based on evidence that f<sub>H2S</sub> and C<sub>H2S</sub> each provide better correlations to SSC at elevated total pressures than P<sub>H2S</sub>. This paper will address the merits and challenges of using f<sub>H2S</sub> or C<sub>H2S</sub> to define sour severity: We argue that C<sub>H2S</sub> is a practical, experimentally verifiable approach, which can be used to validate ionic-equation of state (EOS) frameworks used to characterize mildly sour HPHT environments.

Fit For Service Qualification for Sour Service High Strength Production Casing For High Temperature

In recent years the application of high strength carbon steel with 125ksi specified minimum yield strength as a production casing in deepwater and high-pressure reservoirs has increased. Sulfide stress cracking (SSC) can develop when high strength carbon steel is exposed to a sour environment. The H2S partial pressure in these sour reservoirs is above the 0.03 bar limit for this material at room temperature. Materials SSC performance evaluation requires an accurate simulation of field conditions in the laboratory. To evaluate the production casing SSC behavior, some fit for service (FFS) tests were carried out considering the well geothermic temperature profile for the materials selection. This paper presents a fit for service qualification carried out on Casing 125 ksi SMYS (Specified Minimum Yield Strength) materials. Two products with 125ksi SMYS were considered: one that has existed for several years and one developed more recently with a better SSC resistance – above the pH2S limit considered for the standard 125ksi SMYS material. The results obtained in this test program allowed casing 125 ksi SMYS materials selection for temperature above 65°C and environment more severe in terms of pH2S than the domain previously established for this grade. This allowed a new well production design, which saves one casing phase and avoids the necessity to use intermediate liners to prevent collapse.

18 3/4" 15000 Psi Shear Anything KBOS for Subsea Well Applications

Kinetic Pressure Control has developed the 18 ¾" 15000 psi blowout stopper (KBOS) system for applications on all subsea well activities. The 18 ¾" 15000 psi systems builds upon the successful development of the 5-1/8" 15000 psi KBOS system for surface BOP applications[5]. The system can be configured within the existing subsea BOP, by replacing a casing shear ram or blind shear ram, or can be configured as a shut-in device below the BOP. The KBOS system provides a significant improvement over existing shear ram technology, providing the ability to shear/seal any items in the wellbore, which reduces the likelihood of a blowout, resulting in an improved risk profile. The KBOS is a proprietary design which uses a pyro-technical, electrically initiated process the actuate the shearing process. The system has been designed and tested to actuate and shear/seal in milliseconds, under full wellbore flowing conditions and meets NACE/ISO sour service requirements without exemptions. The control system includes real-time monitoring and function testing capabilities, and requires minimal in-service maintenance, as the working components are isolated from the wellbore fluids. A computational predictive model has been developed, with a test regime conducted to validate the model results. A full qualification program, with 3rd party certification, has been completed to industry standards. Shearing tests have been conducted for a large range of tubulars which have been challenging to shear with existing technology. These include: 9 ½" drill collars, combinations of large OD casing and inner strings, high strength drill pipe and tool joints, wireline, and production tubing. A subsea test of the system was successfully performed in 2019 to shear large OD casing and inner string. The KBOS system utilizes technology from other industries (ballistics, military, automotive) to provide improved shearing and sealing capabilities for all well activities (drilling, completion, intervention). The improved shearing/sealing capacity and reduced time enable a reduced likelihood of a blowout and improved risk profile