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This paper summarizes the results of an examination of the sulfide stress cracking (SSC) susceptibility of selected API and non-API grades of high-strength steels subjected to extensive laboratory and field tests. Introduction High-strength steels commonly used in drilling, completing, and producing' gas and oil wells exhibit catastrophic, brittle failures when exposed to environments containing hydrogen sulfide. This phenomenon is known as sulfide stress cracking (SSC). SSC has long troubled the petroleum industry by placing restrictions on the use of petroleum industry by placing restrictions on the use of high-strength steels in handling sour gas and crude in these applications. As wells become deeper and encounter higher temperature and higher pressure formations, these high-strength steels are needed for effective, economic, and safe completions. High priority is placed on comprehensive design guidelines for commonly used highstrength steels that will allow selection of these materials for specified conditions of temperature and H2S concentration. Many previous studies have used laboratory tests incorporating artificial H2S environments (100 percent H2S, NaCl, HCl, H2SO4, etc.) to investigate the various parameters that affect SSC of steels. Often these studies parameters that affect SSC of steels. Often these studies have failed to relate the laboratory data to observations made in real oilfield environments. Generally, SSC data for many conventional oilfield materials are not available. This paper summarizes the results of an examination of the SSC susceptibility of selected API and nonAPI grades of high-strength steels subjected to extensive laboratory and field tests. The objective of these tests was to determine the limits of SSC susceptibility for these materials in real oilfield environments and to correlate these results with laboratory data. Test Procedure Materials Table 1 lists the materials tested in the present study, along with their chemical compositions. Five API grades of steel tubulars were tested: J-55, C-75, N-80, P-110, and V-150. The non-API steels tested included MOD N-80 (trade mark), SOO-95 (trade mark), SOO-125 (trade mark), and SOO-140 (trade mark). Also included in this examination was a sample of AISI 410 in wrought tubular form. All materials with the exception of the SOO-140 were in the form of 3 1/2- to 4 1/2-in. casing. The SOO-140 was in the form of 7-in. casing. The mechanical properties of these steels are given in Table 2. All materials were heat treated by the supplying manufacturer. Specimens All materials with the exception of the SOO-140 were tested in the form of notched C-rings. An example is shown in Fig. 1. The C-rings were approximately 4 1/2-in. in diameter (3 1/2-in. diameter for SOO-125) with a 0.25-in. wall thickness. The outside surface of each specimen contained a Charpy V-notch, which had a depth of 12 1/2 percent of the specimen thickness. The SOO-140 was tested in the form of notched beam specimens (3.5 X 0.3 X 0.1-in., 12 1/2 percent Charpy V-notch). Such a specimen is also shown in Fig. 1. All specimens were stressed by mechanical deflection using carbon-steel bolts, while neglecting the effect of the C-ring notch. JPT P. 1483

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Distinguished Author Series articles are general, descriptiverepresentations that summarize the state of the art in an area of technology bydescribing recent developments for readers who are not specialists in thetopics discussed. Written by individuals recognized as experts in the area, these articles provide key references to more definitive work and presentspecific details only to illustrate the technology. Purpose: to informthe general readership of recent advances in various areas of petroleumengineering. Summary This paper provides a technical review of the materials selectionprocess for sour service. It highlights H2S corrosion processes that occur onhigh-strength steels and corrosion-resistant alloys. In addition, procedures toperform materials evaluation and selection to minimize the deleterious effectsof H2S are discussed. Introduction As shallow reserves are depleted, the worldwide search for new sources ofhydrocarbons is turning to deeper reservoirs. Drilling and producing thesereservoirs requires the use of new materials not previously used. In manysituations, drilling procedures and completion schemes are now being dictatedby materials technology. Deeper drilling means that higher pressures will be encountered and that thereservoir fluids will be at a higher temperature than normal. The likelihood ofencountering acid gases (CO2 and H2S) as a reservoir component is alsoincreased. Formations containing 25% H2S + CO2 at 200 deg. C [392 deg. F] witha bottomhole pressure of more than 140 MPa [20,000 psi] are not uncommon. The mechanical requirements for materials used for production equipmentincrease substantially with well depth. Tensile loads for tubulars are greaterbecause of the greater hangoff loads, and hoop stresses increase because ofpressure. Elevated temperatures have a pronounced detrimental influence onmechanical properties. The tradeoff in economics is often between higher-strength(higher-price-per-pound) materials and thicker-walled equipment (more pounds). In most cases, higher-strength materials would be favored economically were itnot for the greater susceptibility of high-strength materials to environmentaldegradation in reservoir fluids. This paper discusses (1) the environmentalprocesses associated with H S that affect the performance of high-strengthmaterials, (2) the alloys that are used (or are being considered) to overcomethe adverse effects of corrosive environments, and (3) procedures to selectmaterials for sour service. The more difficult frontier areas where wells aredeep and hot and contain acid gas have been emphasized. Historical Background Since the early 1950's, the petroleum industry has been developing sour-gasfields. Initially, much of this activity was centered in western Canada. Asfield operations began, it was quickly realized that there was a major problemwith brittle fracturing, later called sulfide stress cracking (SSC), ofhigh-strength (high-hardness) steels when exposed to sour productionenvironments. This problem was particularly associated with the failure ofdownhole production tubulars. However. other consequences of exposure to sourenvironments were quickly recognized. JPT P. 1051^