As the severity of sour drilling applications has increased the need for drill stem materials resistant to Sulfide Stress Cracking (SSC) has accelerated. This is especially true in the Middle East with some of the most severe H2S environments in the world. Sour service drillpipe, built with SSC resistant tubes and tool joints, has been available for some time. The friction welds joining the tubes and tool joints were not SSC resistant. This has been acceptable for many sour applications since the weld is not the high stress area of the drillpipe and because the operator has some control over the environment through the drilling fluid properties and additives. As more severe H2S environments were identified for exploration, it became apparent that a fully SSC resistant drillpipe system including the friction welds was necessary. This paper presents the successful development of SSC resistant friction welds for critical sour applications. It describes the engineering and manufacturing philosophy, laboratory testing procedures and results and applications for the SSC resistant drillpipe. Since NACE MR-0175 does not cover friction welds the engineering team developed unique and innovative criteria and testing procedures. A new patent pending four point bending test procedure and fixture were develop that employed unpolished samples that represent the surface finish of the product in service, unlike polished samples typically used in NACE TM-0177 testing. This paper provides background information on the evolution of sour service drillpipe and reviews case histories where sour service drillpipe has been successfully used including the new pipe with SSC resistant friction welds. A preview of some vital planning considerations for an upcoming world-class ERD well in Saudi Arabia with high H2S concentrations is also included. The paper can benefit drilling engineers involved in critical sour drilling operations in the Middle East and other world regions.
Sour Service Drillpipe
The drillpipe assembly incorporates a tool joint that is typically manufactured from a forging and a friction weld that attaches the tool joint to the upset of the pipe body. This is the same manufacturing configuration that has been employed on drillpipe for decades and has been adapted to incorporate materials that resist SSC for critical sour applications. The manufacturing technology for critical service drillpipe has evolved significantly in the last several years. Major advances relating to pipe specifically developed for use in areas with significant H2S content have been realized.
Sulfide Stress Cracking (SSC) due to the presence of H2S gas in the downhole drilling environments has led to the development of sour service drillpipe, which is engineered to have resistance to SSC. Previously available sour service drillpipe was comprised of an SSC resistant upset to grade tube and tool joint. The friction weld areas that are used to join the tool joints to the upset ends of the tubes were not manufactured for resistance to SSC.
Case, Raymundo (ConocoPhillips) | Rincon, Hernan (ConocoPhillips) | Tang, Xuanping (Institute for Corrosion and Multiphase Technology, Department of Chemical and Biomolecular Engineering, Ohio University)
Cai, Feng (Corrosion and Protection Center, Institute for Advanced Materials and Technology, University of Science and Technology Beijing) | Liu, Wei (Corrosion and Protection Center, Institute for Advanced Materials and Technology, University of Science and Technology Beijing) | Fan, Xuehua (Beijing Branch of China Petroleum Engineering co, Ltd) | Lu, Minxu (Corrosion and Protection Center, Institute for Advanced Materials and Technology, University of Science and Technology Beijing) | Zhang, Jing (Corrosion and Protection Center, Institute for Advanced Materials and Technology, University of Science and Technology Beijing) | Du, Qing (State Key Laboratory for Advanced Metals and Materials, University of Sciences and Technology Beijing)
Honda, Hiroshi (Inpex Corporation) | Sunaba, Toshiyuki (Inpex Corporation) | Tomoe, Yasuyoshi (Inpex Corporation) | Watanabe, Tomoko (Japan Oil, Gas and Metals National Corporation) | Foss, Martin (Institute for Energy Technology)
ABSTRACT Loop testing has been carried out to identify the corrosion for 13Cr SS, modified 13Cr SS and 15Cr SS under 2 MPa CO2 in 20,000 ppm NaCl solution with varying concentrations of H2S and organic acids at a temperature of 40°C. It is found that the corrosion behaviors of the steels strongly depend on H2S and organic acids. The results indicate that the 13 Cr SS corrodes significantly at 2 MPa CO2 conditions with H2S present. The modified 13 Cr SS and 15 Cr SS show very good corrosion resistances under CO2 with different H2S partial pressures from 0 to 0.002 MPa. However, severe pitting and general corrosion are observed under the CO2-H2S environments with 0.01 and 0.02 M acetic/propionic acids for both modified 13 Cr SS and 15 Cr SS. INTRODUCTION High CO2 partial pressure and trace amount of H2S have been predicted in current gas development wells. Moreover, very high concentrations of organic acids and chloride in the formation waters have been forecasted. In order to prevent high risk of corrosion caused by these serious environmental factors, corrosion resistant alloys (CRAs) have been widely used in current gas development wells. It is well know that some expensive CRAs, such as 22Cr duplex stainless steels, show very good corrosion performance in CO2 environment with a trace amount of H2S.1 Because of high cost, application of these alloys becomes limited. The 13Cr SS, which is one of the cheap CRAs, was used as a tubing material in the Minami-Nagaoka gas field.1 After in service about 4 years, unfortunately, severe localized corrosions were observed in the tubing located at the shallow parts of the wells shown in Figure 1. It was assumed that the 13Cr SS lost the ability of repassivation due to the high concentration of acetic acid and low pH caused by high CO2 dissolution at low temperatures.
ABSTRACT Aluminide coatings were applied by halide activated pack cementation to austenitic 304 stainless steel substrates. The evolution of coating microstructure as a function of coating process parameters, e.g., temperature, time, etc., was explored. Stainless steel type 304 was chosen as a model substrate to understand the kinetics of aluminizing and for the potential enhancement in high temperature corrosion resistance. The kinetics of the aluminizing process was studied at different temperatures in the 650 – 850°C range and times in the 1 – 25 h range. At 650°C, the coating consisted of a single layer containing two phases tentatively identified as Al5FeNi (Cr) as the matrix with a dispersed aluminide, Al86Fe14. At 850°C, the coatings initially consist of at least two layers containing three phases [with a preliminary identification as Al86Fe14, AlxFey(Ni,Cr) and Al5Fe Ni(Cr) which transitions to a single layer of possibly AlxFey(Ni,Cr) and intermetallic precipitates of undetermined composition. INTRODUCTION Stainless steels are known to have excellent resistance to attack from corrosive media at both room and elevated temperatures. High temperature corrosion is a potential problem for austenitic stainless steels, e.g., 304, used in chemical processing environments.1 Extension of the operating regime and the life of the base alloy can be achieved by the application of protective coatings. Aluminum-containing coatings form stable protective oxide scales, making aluminum a commonly used coating element and aluminizing a ubiquitous coating process.2,3 In the current study, the halide activated pack cementation process was used to apply aluminum diffusion coatings onto the surface of 304 SS. EXPERIMENTAL PROCEDURE Stainless steel samples were cut into 5 mm thick, 12.5 mm diameter coupons. The samples were then taken through standard metallographic preparation procedures by grinding the surface down to 600 grit using silicon carbide abrasive paper. Packs were prepared by mixing powders of aluminum oxide (“filler”), aluminum (“masteralloy”) and aluminum chloride (“activator”).
Cheng, XingGuo (Southwest Research Institute) | Desai, Sapna (Southwest Research Institute) | Gutierrez, Gloria (Southwest Research Institute) | Wellinghoff, Stephen (Southwest Research Institute) | Rossini, Gorge (Southwest Research Institute) | Bredbenner, Todd (Southwest Research Institute) | Yu, Hui (Southwest Research Institute)