Tubular Goods Research Articles

SUMITOMO SM125S

Abstract Sumitomo SM125S is a low alloy high strength carbon steel for use in oil country tubular goods as a material suitable for medium severity sour service. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: CS-191. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

SUMITOMO SM125ES

Abstract Sumitomo SM125ES is a low alloy, high strength carbon steel for use in oil country tubular goods as a material suitable for high severity sour service. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: CS-190. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

SUMITOMO SM110XS

Abstract Sumitomo SM110XS is a low-alloy, high-strength carbon steel for use in oil country tubular goods as a material suitable for sour service. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: CS-188. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

SUMITOMO SM90XS

Abstract Sumitomo SM90XS is a low alloy carbon steel for use in oil country tubular goods as a material suitable for sour service. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: CS-187. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

SUMITOMO SM80XS

Abstract Sumitomo SM80XS is a low alloy carbon steel for use in oil country tubular goods as a material suitable for sour service. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: CS-185. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

Investigation of stress corrosion cracking behavior of super 13Cr tubing by full-scale tubular goods corrosion test system

In this paper, a self-built device called “full-scale tubular goods corrosion test system” was used to test a 6m length super 13Cr tubing (with coupling) to study its corrosion performance in spent acid. The specimen fractured at the tubing and was investigated by visual inspection, optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and mechanical test. It was the joint function of tensile force (78.6% actual yield strength), inner pressure (70Mpa) and spent acid that induced stress corrosion cracking (SCC) of the tubing at 120°C. Three different areas were found on the fracture surface, including crack initiation area, crack expansion area, and final fracture area. The fracture initiated from the “X” shape corrosion cracks which were evolved from small corrosion pits. The reduction of ductility and toughness may also facilitate SCC of the tubing.

Investigation of pH2S influence on 3% Cr tubing steel corrosion behaviours in CO2–H2S–Cl− environment

A series of experiments were conducted in autoclave to investigate corrosion properties of low Cr oil country tubular goods in CO2/H2S saturated brine solution (3 wt-%NaCl) at 90°C. Test material is 3Cr-80, which is gradually accepted in oil and gas industry, especially for downhole tubing and casing. The CO2 partial pressure was fixed at 4·0 bar in all experiments, and the H2S partial pressure was varied from 0, 2, 4, 8, 20, 40 and 800 mbar to 4000 mbar (4 bar). The results show that when the pH2S varied at a lower range (2–40 mbar), 3Cr-80 materials’ corrosion rates were restricted, and coupons’ surface morphologies became glossy compared to the pure CO2 corrosion. Under the condition of pH2S = 800 mbar, H2S no longer have a retardation effect on CO2 corrosion but acceleration. The average corrosion rate was higher than pure CO2 corrosion. When the pH2S rise to 4000 mbar (equal to the CO2 partial pressure), 3Cr corroded much more severe and serious mesa attack was observed.

Theoretical and Experimental Study of Bimetal-Pipe Hydroforming

The corrosion of oil country tubular goods (OCTG) gets more and more serious especially in the acidic environment. So, it is very important to develop a perfect anticorrosion technology for exploring sour oil and gas fields economically and safely. Analysis indicates that the bimetal-pipe (BP) which consists of the base layer of low carbon steel and a corrosion resistant alloy (CRA) cladding layer is an economic and reliable anticorrosion technology and has broad application prospects in the transportation of acid medium. However, theoretical study of hydraulic expansion mechanism for BP is not enough. In this paper, the deformation compatibility condition of BP was obtained by studying the deformation rule of the (CRA) liner and the outer pipe of carbon steel in the forming process; the mechanical model which can compute the hydroforming pressure of BP has been established based on the nonlinear kinematic hardening characteristics of material; furthermore, based on the stress strain curve of inner pipe simultaneously, the calculation method of the plastic hardening stress has been proposed. Thus, the accurate method for computing the forming pressure was obtained. The experimental data show that results are consistent with results of the proposed model. It indicates that the model can be used to provide theoretical guidance for the design and production as well as use of BP.

Investigation on Material Selection in Missan Oilfields Similar Environment

This paper analyzed the corrosion environment of Missan oilfields and investigated the oilfield country tubular goods used in other similar oilfields. Summarized the effect of partial pressure ratio of H2S/CO2 and Cl-to the corrosion behavior of OCTG. This paper concluded the service condition, test results and anti-corrosion mechanism of carbon steel, low-chrome steel, modified martensitic stainless steel and nickel alloy. Finally arrived at conclusion that the nickel alloy can meet the requirement of Missan oilfields, some literature reported that the modified martensitic stainless steel can apply in H2S/CO2 environment. In the condition that be easy to replace the tubular, carbon steel and low-chrome steel tubular can meet the requirement with corrosion inhibitor.

Influence of Deformation on Phase Transformation and Precipitation of Steels for Oil Country Tubular Goods

This work presents different modeling approaches for the description of the microstructure evolution in a typical C–Mn micro‐alloyed steel for pipes and tubes in the oil field industry. A comparison between the continuous‐cooling‐transformation (CCT) diagram of the material with no deformation and the DCCT diagram after single‐ and multiple‐step deformation is presented. The experiments are performed on a high‐speed deformation dilatometer. The start of austenite decomposition is simulated with the software JMatPro, whereas the bainite and martensite start temperature are additionally evaluated with empirical formulae available in the literature. The precipitation state of the micro‐alloying elements is investigated by transmission and scanning electron microscopy and compared with calculated ones by using the software package MatCalc. Our simulation results are directly applicable to the optimization of microstructure and properties in the production of steels for oil country tubular goods.

OCTG Premature failures Due to Metallurgical Variance and Differential Electrochemical Behaviour of Exterior and Interior Walls

Previous studies on oil well’s unpredicted failures referred to uncertainty in interpreting the phenomenon of the prone of the external walls of Oil Country Tubular Good OCTG to the corrosion attacks more than the interior walls. In this study the tubular goods standards, failure analyses procedures and manufacturing tubular processes are reassessed. Theoretically manufacturing processes must show differential metallurgical heredities and residual stresses on OCTG exterior and interior walls. This fact regarded as an insignificant issue on most corrosion failure analyses, whereas any cut of the base metal from anywhere of a pipe, supposed to represents overall pipes in services condition. In this study, Full Ring Corrosion Cell Kit (FRCCK) setup has been built and full ring specimens prepared from L-80 grade tubing. Open circuit and galvanic corrosion tests have been run on exterior and interior walls separately in multi-concentration brines. Metallography shows slight difference of the microstructure and the ferrite/perlite phase’s ratio between inner and outer surfaces, but electrochemically the results indicate that there are significant differences of corrosion behaviors between exterior and interior surfaces. This approach may lead to reassessment of tubular goods corrosion manufacturing processes, inspections, failure interpreting, designing, specifications and quality standards, by cheap, fast, and reliable electrochemical non-destructive testing (NDT).

Corrosion in the Oil and Gas Industry: An Increasing Challenge for Materials

Important reserves of oil and gas, which are left to be discovered and produced, are mainly concentrated in challenging locations and under severe conditions [i.e., high pressure (HP)/high temperature (HT)]. The HP/HT plus the presence of aggressive environments mean a highly demanding scenario for tubes used in producing oil and gas [oil country tubular goods (OCTG)]. Material property requirements include high mechanical properties at ambient and high temperatures (e.g., as high up to 200–250°C). Additionally, if H2S is present, resistance to sulfide stress cracking may be required, depending also on other environmental conditions. Even without H2S, contents of CO2, chlorides, and high temperatures and pressures can represent a risk of high corrosion rates. The improvement of some of the required properties of the materials (e.g., steels) can mean the impairment of other properties. Consequently, a careful balance is required and limits exist for the individual modification of the properties. The present article focuses on the two main environmental deterioration problems in the oil and gas business: (I) sulfide stress cracking and (II) CO2 corrosion. A description of the acting mechanisms and the effect of environmental and material factors are presented. Selection criteria and current material limitations are also discussed.

The Field Inspection and Research of Related Problems about a Kind of Non-API Thread Connections

Compared with API (American Petroleum Institute) OCTG (Oil Country Tubular Goods) thread, Non-API thread OCTG has excellent sealing performance and high joint strength for greater depth, higher pressure and temperature, other more rigorous working conditions as well. This paper describes the special structures of a kind of Non-API connection in specific, which is widely used in domestic oil field and gas storage, detailed examination of this connection and recommended practice to measure its thread. So as to provide some useful reference and help for field inspection, it also focuses on the connection’s unusual measure items and points some problems in the process of thread inspection.

Stability Analysis of Pipe With Connectors in Horizontal Wells

Summary Except for coiled tubing, most tubular goods used for downhole operations (such as drillpipe and sucker rod) have connectors. Because a connector and the pipe body have different outer radii, the deformation and buckling behavior of a pipe with connectors constrained in a wellbore is much more complicated. However, most buckling models were established by neglecting the existence and effects of connectors. In this paper, buckling equations of a pipe with connectors in horizontal wells were derived with application of elastic-beam theory. The axis of an unbuckled pipe is a 2D curve in the vertical plane and has three configurations—no contact, point contact, and wrap contact. We derived the two critical distances between connectors, Lc1 and Lc2, beyond which a pipe changes its configuration from one to another. The authors proposed an algorithm to determine the critical force (Fcrs) of buckling by numerically solving the buckling equations using the fourth-order Ronge-Kuta method. Both the distance between two adjacent connectors (Lc) and the radius difference between a connector and the pipe body (∆rc) have significant impact on the critical force, in addition to net clearance between a pipe and wellbore (r0), bending stiffness (EI), and weight per unit length (w) of pipe. When Lc is small, radial deflection is negligible. Fcrs increases as ∆rc increases. However, when Lc is close to Lc1, effects of radial displacement become significant, and Fcrs decreases dramatically as ∆rc increases. Fcrs decreases as Lc increases when Lc Lc1, and it reaches its minimum at Lc=Lc1. When Lc > Lc1, Fcrs fluctuates as Lc increases. Some curves of Lc1, Lc2, and Fcrs, all in dimensionless forms, were calculated and presented in this paper for practical applications. Our numerical results show that the critical force may reduce by 20 to 60% for commonly used drillpipes and sucker rods with centralizers, which indicates that a pipe string designed without considering the effects of connectors may be risky. The results presented in this paper may provide some practical guidance for optimal design of centralizers for sucker-rod strings, or may avoid some risks because of improper design of drillpipe strings.

Burst Strength Prediction of OCTG

With high pressure high temperature (HPHT) oil & gas wells increasing, oil country tubular goods (OCTG) service environment tends to be critical complex. In these critical oil & gas wells, when burst failures of high strength service grades for downhole applications once take place, the H2S gas may be run freely between tubing and intermediate casing, intermediate casing and surface casing, even the sulfur-containing gases spring ground, the harm is self-evident. Therefore, an accurate prediction of the burst strength, which is defined as the maximum value of internal pressure required to cause the steel casing to fail, is a very important consideration in the casing design process. The burst model has been provided in ISO/TR10400:2007, but almost half of the predictionts exceed the test burst strength. So this paper develops a new model that incorporates the influence of yield-to-tensile strength ratio on burst failure of casing and tubing without defects.

Research on Corrosion of Well-Bore Tube and Anticorrosive Measure of Tazhong-1 Gas Field

Natural gas of Tazhong-1 gas field contains 7.7% carbon dioxide and 2.31% hydrogen sulfide, and produced water salinity is up to 140000mg/L,the well-bore tube has seriously potential corrosion destructive with natural gas being exploited. Based on the corrosion type partition of down-hole tube for eighteen production wells of Tazhong-1 gas field, P110,P110S and P110SS corrosion behavior were investigated under the conditions of simulated formation water containing carbon dioxide or hydrogen sulfide/carbon dioxide, and corrosion inhibitors were chosen to meet need of anticorrosion of Tazhong-1 gas field. The results show that fifteen wells in eighteen production wells belong to hydrogen sulfide corrosion of both hydrogen sulfide and carbon dioxide influence. Other wells are singular carbon dioxide corrosion. The most severe corrosion of three types of down-hole tubes all occurs at 90°C in both corrosion media, and their corrosion resistance order is respectively P110>P110S>P110SS and P110S>P110SS>P110 under the conditions of simulated formation water containing carbon dioxide or hydrogen sulfide and carbon dioxide. The selected anti-temperature corrosion inhibitors (YU-1、YU-4) can control the corrosion rate of three types of down-hole tubular goods within 0.076mm/a in simulated formation water media with carbon dioxide (PCO2=0.08～4.64MPa) or hydrogen sulfide and carbon dioxide (PH2S/Pco2=1.3/4.64Mpa) while added amount of the inhibitor is 120～300mg/L or 200mg/L. All of these provide technical support for safe and fast development of Tazhong-1 gas field.

Study on the Influence of Cooling Rate on the Property of Non-Quenching and Non-Tempering Steel OCTG

Two industrial produced non-quenching and non-tempering steels 40Mn2V and 36Mn2V had been tested by Gleeble-1500 thermal simulation machine to simulate MPM rolling, sizing and cooling process. The cooling rate in the air noticeably affected the final property of different size pipes. According to the measured practical cooling rates of different size pipes, appropriate size pipes with cooling rate at range of 0.9°C/s~1.6°C/s and 1.6 °C/s~2.1°C/s can be picked out to use steel 40Mn2V and 36Mn2V to produce grade N80 OCTG(Oil Country Tubular Goods) with steady property respectively. This result had been used in practical production, which greatly improved the property stability of grade N80 OCTG.

Dynamic Fracture Toughness Test and Evaluation for S135 Drill Pipe

During oil-drilling, the fractures of drill tool thread and piercement of drill pipe upset transition are very common in drill pipe failure as an object of petroleum and metallurgical researchers home and abroad. The classical fracture mechanics can only resolve the static fracture problem of oil country tubular goods (OCTG), but not resolve drill pipe failure under dynamic load. It is well known that the API 5D just prescribes strength criterion of drill pipe material but fracture toughness of drill pipe material. So, it is important to study dynamic fracture toughness of drill pipe material and present appropriate toughness criterion, which can not only optimize the drill string structural design, but also reduce fracture failure of drill string. On the basis of presenting main test means of dynamic fracture toughness and referring to the Charpy V test, the new impact experiment instrument is developed. Numerical and experimental comparisons show that the repeated dynamic fracture toughness tested by the impact experiment instrument is more accurate than one time impact, which can better show material characteristic and provide a reliable way to distinguish material characteristic, in the meantime, the correlations between dynamic fracture toughness of drill pipe material and failure of drill pipe is obtained.

Effects of Thermo-Mechanical Control Process on the Microstructure and Properties of the Welded Joints of ERW OCTG

In the paper, the effects of thermo-mechanical control process on microstructure and properties of oil country tubular goods by electrical resistance welding are analyzed. The TMCP parameters are optimized by Gleeble-1500 thermo-mechanical simulator, and industrial trial is carried out. The microstructures in the welded joints of original ERW OCTG are mainly composed of proeutectoid ferrite, pearlite and widmanstatten. In contrast, the welded joints of ERW OCTG treated by TMCP consist only of refined ferrite and pearlite. The higher low-temperature impact toughness and the better resistance to the grooving corrosion of the welded joints of ERW OCTG treated by TMCP could be attributed to removing welding residual stresses, homogenizing microstructure, eliminating porosity and refining grain. TMCP facilitates the performance optimization of welded joints so that the quality of the finished product can be improved.

A New OCTG Strength Equation for Collapse Under External Load Only

The influence of manufacturing technology and imperfections on casing collapse strength is not considered in API bulletin 5C3. In the meantime, the current casing true collapse strength cannot be predicted accurately by API bulletin 5C3. For these cases, the joint API/ISO work group ISOTC67 SC5 WG2b has proposed the current API bulletin 5C3 and presented a new collapse strength model with manufacturing imperfections, such as ovality, eccentricity, residual stress, etc., which improves the casing strength calculation accuracy and benefits much more for casing strength design rather than just using API bulletin 5C3. The study on the new ISO collapse model has found that it cannot be used to predict the collapse strength of all pipe sizes, and the current study results are greatly different from actual conditions, which is not the last goal to propose API bulletin 5C3 for the joint API/ISO work group ISOTC67 SC5 WG2b. So, based on the new ISO collapse model, a new oil country tubular goods (OCGT) strength equation, “new equation” for predicting all OCTG sizes collapse strength under external load only has been presented in this paper. Numerical and experimental comparisons show that there is a safety margin appropriate to the desired target reliability level between the predictive values calculated by the new equation and test collapse data, and the new equation calculation accuracy is higher than that of API and ISO, which will make great improvements in the casing design of deep and superdeep wells on the basis of guaranteeing casing material safety.