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A multifunctional catalyst composed of CoMn and CuZnAlZr oxides can dramatically increase higher-alcohol selectivity. However, the role of Cu-based components and catalytic mechanism are still uncl...

Direct synthesis of aromatics from syngas was investigated by coupling Fischer–Tropsch to olefins (FTO) reaction and aromatization process. The CoMnAl composite oxides enabled the formation of olef...

In order to prevent well leakage in high temperature and high pressure (HTHP) wells, pressure test is a very important leak prevention operation that causes artificial high-pressure environment in wellbore. However, failure of wellbore equipment due to harsh condition is a common problem that brings great economic losses. Ram blowout preventer (BOP) is an important component of wellbore integrity, which is subjected to heavy loads from the test gas and the push rod during the pressure test. Therefore, the serious stress concentration of ram BOP induced by heavy loads and complex geometry is a major reason of fracture. Hence, the focus is to find out the fracture mechanism of ram BOP with experimental method and finite elements (FE) model in this paper. A series of damage inspection and strength test of ram BOP is carried out to find out the fracture characteristics. Based on detection information, FE analysis is conducted to analysis stress distribution and fracture reason of ram BOP. The results show that the maximum stress exceeds the yield strength (705 MPa) of the material under the actual working condition. Serious stress concentration at the notch root of the ram BOP can be easily caused by test pressure (from test gas) and contact pressure (from push rod). Both experimental method and FE analysis show the characteristics of ductile fracture obviously. Stress concentration at notch root is very sensitive to the test pressure. The work presented in this paper can provide basis and reference for preventing failure of ram BOP and improve efficiency and production.

Direct production of olefins via syngas conversion over a Co2C-based catalyst was investigated in a slurry bed reactor (SBR). It was found that the total selectivities to olefins and oxygenates reached 88.8C% at a CO conversion of 29.5% at 250 °C, 5 bar and H2/CO = 0.5. The hydrocarbon distribution greatly deviated from the classical Anderson–Schulz–Flory (ASF) distribution, with only 2.6C% methane selectivity was obtained. XRD and TEM characterization verified that the Co2C nanoprisms with special exposed facts of (101) and (020) constitutes the Fischer–Tropsch to olefins (FTO) active site. The catalytic activity increased gradually with rising the reaction temperature, while the product distribution almost kept unchanged under various reaction condition in SBR. Compared to the reaction in FBR, the Co2C-based catalyst exhibited relative better catalytic performance during FTO process in SBR. Specifically, a higher CO conversion, a lower methane selectivity and a higher total selectivities to olefins and oxygenates were achieved in SBR. In addition, the catalyst can be in situ reduced in slurry bed reactor at mild temperature (300 °C) and no obvious deactivation was found within nearly 100 h time-on-stream, which suggested a promising route for the direct production of olefins via syngas in industrial application.

Co2C-based catalysts with SiO2, γ-Al2O3, and carbon nanotubes (CNTs) as support materials were prepared and evaluated for the Fischer-Tropsch to olefin (FTO) reaction. The combination of catalytic performance and structure characterization indicates that the cobalt-support interaction has a great influence on the Co2C morphology and catalytic performance. The CNT support facilitates the formation of a CoMn composite oxide during calcination, and Co2C nanoprisms were observed in the spent catalysts, resulting in a product distribution that greatly deviates from the classical Anderson-Schulz-Flory (ASF) distribution, where only 2.4 C% methane was generated. The Co3O4 phase for SiO2- and γ-Al2O3-supported catalysts was observed in the calcined sample. After reduction, CoO, MnO, and low-valence CoMn composite oxide were generated in the γ-Al2O3-supported sample, and both Co2C nanospheres and nanoprisms were identified in the corresponding spent catalyst. However, only separated phases of CoO and MnO were found in the reduced sample supported by SiO2, and Co2C nanospheres were detected in the spent catalyst without the evidence of any Co2C nanoprisms. The Co2C nanospheres led to a relatively high methane selectivity of 5.8 C% and 12.0 C% of the γ-Al2O3- and SiO2-supported catalysts, respectively. These results suggest that a relatively weak cobalt-support interaction is necessary for the formation of the CoMn composite oxide during calcination, which benefits the formation of Co2C nanoprisms with promising catalytic performance for the sustainable production of olefins via syngas.

According to the tubing string failure statistics in the oilfield, fatigue crack of tubing joint thread in high temperature high pressure (HTHP) ultradeep gas wells remains a problem because it can cause tubing strength degradation, tubing fracture failure, well workover, and even well abandonment. In order to obtain a better understanding of tubing thread fatigue and quantify the fatigue life of tubing joint thread in HTHP ultradeep wells, experimental study, elastic–plastic mechanical simulation, and multi-axial fatigue calculation are carried out in this paper. Based on the similarity theory, the vibration mechanical testing device of the tubing string is designed, and the multi-axial load of the tubing joint thread in the actual working condition is obtained. Meanwhile, tubing joint BX1 thread model is established with ansys software, and the stress distribution of tubing joint thread is analyzed on the boundary condition acquired from experiments of vibration test of tubing string. Finally, according to the multi-axial fatigue theory, the fatigue life prediction value of the tubing thread made of Super 13Cr110 and Super 15Cr125 is compared and analyzed. The work presented in this paper can provide theoretical method and technological basis for the study on the frequent failure mechanism of tubing joint thread in HTHP ultradeep gas wells.

The fracture toughness (KIC) of high strength casing steel (1130 MPa) has been determined by a three-point-bend specimen. Three specimens with thicknesses of 5 mm, 8 mm and 10 mm, respectively have been used to observe the effect of thickness on the fracture toughness of steel. The analytical formula of the relationship between the fracture toughness and material thickness of high strength casing (1130 MPa) is proposed based on the energy theory and on linear elastic mechanics. The values of fracture toughness, K, measured by three thicknesses of parent metals are combined with the quantitative model of the relationship between fracture toughness and specimen thickness. The material constant (and κ) are calculated by using the least squares method. Furthermore, an analytic formula for the relationship between fracture toughness and specimen thickness is proposed which allows for the calculation of the KIC value. Plane-strain fracture toughness (KIC = 133.94 MPa × m1/2) is a fixed value only if the thickness of the specimen exceeds 43 mm. Fracture toughness values of different thicknesses of high strength casing are derived by fracture toughness tests of several thicknesses based on the model in question in order to save manpower and material resources. This method is also significant for measuring the fracture toughness of other OCTG, since their thicknesses do not meet the requirement of the standard test methods. For the present, it provides general methods and reference rules for obtaining the KIC of other metallic OCTG.

Fischer-Tropsch synthesis (FTS) is a structure-sensitive reaction for sustainable production of green fuels and value-added chemicals via syngas derived from coal, biomass, shale gas and natural gas. The nanostructure of a Fischer-Tropsch (FT) catalyst plays a crucial role in its catalytic performance. This review summarizes recent advances in the investigation of nanoeffects of FT catalysts, especially the effects of the active phase, particle size and exposed facet on catalytic performance. Perspectives and challenges for further research in nanocatalysis for syngas conversion are also given.

Flowerlike ZIF-67 micro/nano composite structures were developed by the evolution of ZIF-67 rhombododecahedrons ZIF-67(r) via facile ion-assistant solvothermal treatment. The morphology evolution of ZIF-67 with time-on-stream was studied. The flowerlike Co3O4 micro/nano composite were formed under calcination at relatively low temperature. The flowerlike Co3O4 micro/nano composite structures showed good catalytic properties for photocatalytic degradation of RhB (83.2%), higher than that of Co3O4(p) (69.7%) and Co3O4(r) (75.7%) after 90 min irradiation.

Drillstring vibration is one of the primary causes of drillstring failure, well trajectory deterioration, excessive bit wear and low rate of penetration. In order to obtain an improved understanding of drillstring vibration when drilling horizontal wells, an experimental drillstring system is established in this paper on the basis of drillstring dynamics equations and similarity principle. The system is capable of simulating the nonlinear dynamic behaviors of horizontal drillstring. Axial, lateral and torsional vibration phenomena are investigated in steady state. Experimental results indicate that axial force fluctuates wildly when drillstring is buckled. The fluctuation of WOB (weight on bit) is a typical sine curve and the frequency of WOB increases linearly with rotary speed. The lateral vibration is much more severe than axial vibration for horizontal drillstring. According to similarity principle, in order to reduce lateral vibration, the proposed rotary speed range is 37.5 rpm–50 rpm for the actual horizontal drilling operation. The whirling speed amplitude and frequency of horizontal drillstring increase with rising rotary speed. Stick-slip can also occur in horizontal drilling where the rotary speed of bit involves periodic fluctuation varying almost from zero to about twice the surface rotary speed. The work presented in this paper can provide a technological basis for drillstring dynamics and vibration analysis of horizontal wells.

One reason for unpredictable failures in pipeline operation is third-party damage (TPD), which can occur due to actions of any third parties other than pipeline staff. Based on nonlinear dynamics theory, we propose a finite-element model for impact between an excavator bucket and the pipeline surface. The simulation was done for the following situations: gas transportation, bucket tooth striking the pipeline, bucket tooth separating from the pipeline, and unloading the pipeline pressure. We analyzed the pipeline damage mechanism and established the influence of the dent depth on residual strain and residual stress. Comparison of finite-element results with the standard criteria described in the standard ASME B31.8 showed that the latter criteria have a number of disadvantages.

Microseismic data and production logs in our study area have confirmed an asymmetric development of the stimulation rock volume, while severe casing deformation problems have been reported frequently in this area. In this paper, we investigate the possibility of casing failure due to strong shear stresses developed by asymmetric stimulated zones. Overlapping stimulation zones in adjacent stages may intensify asymmetry of the pore pressure distribution and resultant shear forces. Although induced shearing may have a positive impact on fracture permeability, but it may also cause operational problems by inducing severe casing deformations. While most of the casing deformation models only consider rock deformations very close to the wellbore, we developed a 3D coupled model for fracture network growth and stress re-distribution during hydraulic fracturing to achieve a more realistic model for casing deformation. This reservoir-scale model is tied to a more detailed near-wellbore model including the casing and cement sheath to simulate casing deformations. Case studies were conducted using data from a shale gas well that experienced severe casing deformation during hydraulic fracturing. Impact of stage spacing, and pumping rate are incorporated to investigate their potential impacts on casing and well integrity. Multi-stage hydraulic fracturing considering the development of complex fracture network is simulated at the reservoir scale based on the microseismic events. Continuous re-distribution and re-orientation of stress field near the borehole are tracked during the development of the fracture network which reveals some pocket of tensile stresses along the casing. Asymmetric fractures are observed to generate strong shear stress on the suspended casing. These shear forces result in deflection and S-shape deformations. Some regions receive repeating treatments, which leads to increase formation stress heterogeneity and worsen casing deformation severity. Our analysis has indicated that simply increasing the flexural strength by increasing thickness of casing cannot radically mitigate casing deformation problems. This paper provides a novel workflow for a coupled modelling of casing deformation during hydraulic fracturing operations, while current modelling efforts assume symmetric fracture geometries.

At the high or extra-high temperatures in a natural gas oilfield, where the premium connection is employed by casing, gas leakage in the wellbore is always detected after several years of gas production. As the viscoelastic material’s mechanical properties change with time and temperature, the relaxation of the contact pressure on the connection sealing surface is the main reason for the gas leakage in the high-temperature gas well. In this article, tension-creep experiments were conducted. Furthermore, a constitutive model of the casing material was established by the Prony series method. Moreover, the Prony series’ shift factor was calculated to study the thermo-rheological behavior of the casing material ranging from 120°C to 300°C. A linear viscoelastic model was implemented in ABAQUS, and the simulation results are compared to our experimental data to validate the methodology. Finally, the viscoelastic finite element model is applied to predict the relaxation of contact pressure on the premium connections’ sealing surface versus time under different temperatures. And, the ratio of the design contact pressure and the intending gas sealing pressure is recommended for avoiding the premium connections failure in the high-temperature gas well.

Higher alcohols synthesis (HAS) from syngas with high selectivity attracts great attention but remains challenging. Herein, we reported an effective strategy by tuning chemical environment and synergistic relay reaction to promote the production of higher alcohols. CO insertion rate was greatly enhanced by introducing Rh or Ru component to CoMn oxides. The catalytic activity and oxygenates selectivity increased dramatically over the as-obtained Rh-CoMn or Ru-CoMn catalyst, while the fraction of C2+OH in oxygenates maintained >92 %. Multiple studies demonstrated the highly dispersed Rhδ+ or Ruδ+ species not only effectively tuned the chemical environment and facilitated the stable existence of Co2C, but also catalyzed the coupling of syngas and in-situ generated olefins to produce extra oxygenates via hydroformylation route. The synergistic effect of Co0, Co2C and Rhδ+ (or Ruδ+) species, as well as the promotional effect of olefins relay reaction contributed to the enhancement in both higher alcohols selectivity and CO conversion.

In recent years, the stimulated reservoir volume is a new developing technology applied to the effective exploitation of low permeability shale gas reservoirs. Despite of its superiority and potential, the geostress field is under a complex mechanical environment during the volume fracturing process due to excessive stimulated stages, large fracturing volume, high injection capacity, and increasing dense areas of microseismic events. Based on the drilling and completion data and microseismic monitoring data of Sichuan shale gas horizontal well X201-H1, the three-dimensional finite element model of volume fracturing is established, combining fluid-solid interaction mechanics with the basic theory of rock damage mechanics. According to the established model, the finite element analysis on different fracturing conditions is carried out, which finally results in the stress distribution of near-wellbore area after each staged fracturing operation. The results show that: 1) The change of pore pressure caused by volume fracturing can generate induced stress field, which leads to the re-orientation of in-situ stress field and even the appearance of tension stress areas and zero stress areas within the region of volume fracturing stimulation. 2) The existence of stress field interference in different stages of fracturing operations leads to the change in the magnitude and direction of stress field after each staged fracturing. Research methods and results of the paper will provide guiding significance to the optimization design of staged fracturing of horizontal wells to some extent.

Lower olefins-generally referring to ethylene, propylene and butylene-are basic carbon-based building blocks that are widely used in the chemical industry, and are traditionally produced through thermal or catalytic cracking of a range of hydrocarbon feedstocks, such as naphtha, gas oil, condensates and light alkanes. With the rapid depletion of the limited petroleum reserves that serve as the source of these hydrocarbons, there is an urgent need for processes that can produce lower olefins from alternative feedstocks. The 'Fischer-Tropsch to olefins' (FTO) process has long offered a way of producing lower olefins directly from syngas-a mixture of hydrogen and carbon monoxide that is readily derived from coal, biomass and natural gas. But the hydrocarbons obtained with the FTO process typically follow the so-called Anderson-Schulz-Flory distribution, which is characterized by a maximum C2-C4 hydrocarbon fraction of about 56.7 per cent and an undesired methane fraction of about 29.2 per cent (refs 1, 10, 11, 12). Here we show that, under mild reaction conditions, cobalt carbide quadrangular nanoprisms catalyse the FTO conversion of syngas with high selectivity for the production of lower olefins (constituting around 60.8 per cent of the carbon products), while generating little methane (about 5.0 per cent), with the ratio of desired unsaturated hydrocarbons to less valuable saturated hydrocarbons amongst the C2-C4 products being as high as 30. Detailed catalyst characterization during the initial reaction stage and theoretical calculations indicate that preferentially exposed {101} and {020} facets play a pivotal role during syngas conversion, in that they favour olefin production and inhibit methane formation, and thereby render cobalt carbide nanoprisms a promising new catalyst system for directly converting syngas into lower olefins.

Casing wear during directional well drilling remains a prominent problem because it can cause casing strength degradation, casing deformation and even well abandonment. In order to obtain a better understanding of casing wear and quantify the wear amount in gas drilling of directional wells, theoretical and experimental study is carried out in this paper. Based on casing wear mechanism and energy principle, a prediction model of casing wear is investigated and programmed. Experimental study on casing wear is conducted and casing specimens are worn in air and mud respectively. According to wear morphology analysis, casing wear mechanisms can be recognized as adhesive wear and abrasive wear. Data processing and analysis reveals the influence factors of casing wear, including casing steel grade, rotary speed and contact force. Through linear fitting of test data, wear coefficients in air and mud are obtained and compared. Then the intermediate casing wear of an actual directional well is predicted using the methods and models proposed in this paper with special attention focused on the comparison of wear amount in mud drilling and gas drilling. Prediction results indicate that casing wear is not the major factor restricting the application of gas drilling in directional wells. The feasibility of gas drilling in directional wells is verified in the perspective of casing wear. Finally, optimization of drilling parameters and reducing friction coefficient are proposed for casing wear reduction. The work presented in this paper can provide theoretical foundation and technological basis for casing wear prediction and reduction in gas drilling.

Under the effect of in situ stress in a directional well, the casing wear problem is a highly nonlinear and complicated process. To address this problem, theoretical studies for casing wear in a directional well under in situ stress are studied. Then, casing friction and wear experiments are conducted to obtain the relevant parameters for simulation. Finally, based on the theoretical studies and experimental data, combined with the drilling and well completion data, a finite element model of joint-casing wear for the NP-1 directional well is established. By reprogramming and redeveloping the software with Fortran language, the dynamic simulation of the casing wear process in directional well is realized considering the effects of in situ stress on the wear process. The rules of casing wear depth and residual strength at different locations and different times are obtained, and a new prevention method different from previous measures is proposed. The work presented in this paper can provide a theoretical foundation and technological basis for casing integrity evaluation and casing design in directional wells under in situ stress.

We propose a method for calculating the cuttings (solids) concentration in the annular space and the equivalent circulating density (ECD) in deepwater drilling, both in the pilot hole drilling step and in the reaming step. We have found that drilling a pilot hole followed by reaming has certain advantages over drilling with no pilot hole. When using technology involving preliminary drilling of a pilot hole, the solids concentration in the annular space and the equivalent circulating density are reduced.

Casing integrity is an important category of well integrity in drilling and well operations. Casing integrity defect due to wear and corrosion can cause casing strength degradation, casing deformation and even well abandonment. In this paper, a theoretical model for casing strength degradation due to wear is established in bipolar coordinate system. Another model is established to calculate stress concentration factor of casing with corrosion pit at inner wall. The effects of relevant parameters on residual strength of defective casing are analyzed according to parametric study. According to the stress distribution of casing after wear and corrosion under tri-axial stress, strength check is carried out based on Von Mises yield criterion and Lame thick-walled solution for the pipe. Then, in order to evaluate casing integrity of a real well, casing wear and corrosion experiments are conducted to study mechanisms and obtain relevant parameters for calculation. Finally, according to the established models and experimental results, a modified casing design of this well is proposed considering the effects of wear and corrosion on casing strength degradation. The work presented in this paper can provide a theoretical foundation and technological basis for casing integrity evaluation and casing design of highly-deviated wells or extended-reach wells in sour environment.

With its advantages of lost circulation prevention, drilling speed improvement and reservoir protection, gas drilling technology has been widely applied in Sichuan and Xinjiang oilfields in China . However, drill collar failures have often occurred under high weight on bit (WOB) during gas drilling. These incidents have not only caused serious economic loss but hampered the development and application of gas drilling. Finite element analysis is used to determine the drill collar thread stress distribution and, using simulation of drill string dynamics, multi-axial fatigue life theory is used to calculate the life of a standard API drill collar connection. The computed results reveal the early drill collar fatigue failures in gas drilling. Then, the multi-axial fatigue life of drill collar with double shoulder thread is analyzed under the same loads. Analysis shows that the fatigue life of a double shoulder thread is some thirty times that of the API thread. So drill collar with double shoulder thread could be an efficient way to solve the fatigue failure problems of drill collar in gas drilling. The work presented in this paper can provide theoretical foundations for safe and efficient drilling with gas.

Frequently happening drill pipe failure accidents in oil and gas wells not only affect drilling speed, but cause enormous economic losses and many safety issues. Most of these accidents are transverse cracking of drill pipe body and pin thread or axial cracking of box thread. Based on the axial cracking failures of drill pipe body in an ultra-deep well in China, this paper give a systematic analysis of axial cracking failure in consideration of service condition, material quality and stress corrosion mechanism. Measurement and inspection are performed on macroscopic and microscopic morphology of crack surface, corrosion products and circumferential residual stress. Then stress corrosion cracking experiments against hydrogen sulfide is conducted. Finally, the critical stress value for sulfide stress corrosion cracking of the drill pipe material is obtained, and the mechanisms of axial cracking failure and corresponding preventive measures are proposed.

Pressure vessel is a primary barrier to gathering system and an important guarantee for normal production in the oilfield. Composite materials for pressure vessels are widely used to adapt to acidic media and temperature and pressure environment. Therefore, the stress corrosion cracking (SCC) is easily caused considering harsh working condition and multi-material structure. Pressure vessel defect due to SCC can cause material strength degradation, medium leakage and even explosion. In order to analyze the stress distribution of the whole equipment and verify the crack detection results in the field, a detailed finite elements model (FEM) of the absorber considering the composite material is established based on mechanical experiments and field data. On the other hand, a WOL specimen FEM is established according to the industry standard. Finally, twelve SCC evaluation experiments of composite materials are carried out based on the results of two established FEM, and the safety windows of 316L and SA516-70 are obtained in specific stress corrosion environments. The work presented in this paper can offer a technological basis and theoretical foundation for strength design of composite materials for pressure vessels in sour environment.

Creep or stress relaxation is considered as a mainly factor of reducing the contact pressure on the sealing surface of premium connection, causing the gas leakage in the high temperature gas well. In this paper, the creep tests of P110T casing material were conducted under different temperatures (120, 200, 300 °C). According to the experimental data, the fitting mathematical model of P110T casing material’s steady creep strain rate was obtained under the different temperature and loading by the Least Square method. Then, the relation of creep and relaxation was presented, and an innovation stress relaxation model was put forward from the creep strain rate. Finally, applying with the stress relaxation model, P110T casing material’s stress relaxation varying with time was obtained. The results show that, the stress relaxation was obvious in the initial phase and it decreased with time increasing. The stress decreased significantly and tended to a stable value. And the environmental temperature and initial stress had a significant influence on the stress relaxation. This study can be used for the designing of the premium connection’s structure, or prediction their service life in the high temperature gas well.

Blooey line is a discharge pipe, used to conduct gas to keep drilling rock dust and cuttings away from the drilling rig, reducing the fire hazard and transporting the cuttings to a suitable distance from the well. In this paper, the blooey line's flow capacity and erosion mechanism have been investigated by numerical and experimental method. The model of blooey line, which is commonly used in Sichuan district, China, is established by using a computational fluid dynamics (CFD) method. And, the distribution of pressure field and velocity field in the blooey line are investigated by the CFD model. And, the effect of gas flow rate on impact force and erosion is also discussed. Compared with the simulation results, an experimental apparatus of the blooey line has been conducted under the mechanical similarity principle. The impact force and pressure on the elbows are measured under different gas flow rates. The numerical simulation and experimental method proposed in this paper can provide a reference for layout optimization and flow capacity calculation of blooey line in gas drilling.

With the development of drilling technology and reinforced exploration and exploitation of unconventional reservoirs, there has been a great increase of complex wells. Meanwhile, however, consequent casing wear is and will continue to be a serious problem that causes enormous economic losses and many safety issues. The purpose of this paper is to find out the mechanism of casing wear and establish casing wear prediction model. Casing wear experiment was carried out to study the effect of contact force, rotation speed, and casing grade on wear depth. Meanwhile, wear coefficients under different working conditions were obtained through the normalizing of data. With the extensive research of downhole drag and torque calculation method, a contact force calculation model was established. Through the combination of crescent-shaped model and wear-efficiency model, the past complicated casing wear prediction models and confusing empirical formulae were greatly simplified. Therefore, the wear volume and depth of the casing string can be accurately predicted. Finally, a prediction software was developed to predict downhole casing wear of oil and gas wells. Comparison with the field data confirmed that the established model and software had enough accuracy to help predict and analyze casing wear at field.

A large number of casing failures occur during the volume fracturing operation of shale gas, making normal completion stimulations impossible. To solve this problem, rock mechanical experiments and numerical simulation experiments are carried out in this article. It is found that the macroscopic rock mechanical strength reduces most when the crack angle of fissured rock in Longmaxi Formation is 45°, and it reduces stably when the number of cracks increases to 8. The elasticity modulus ratio, yield strength ratio, and compressive strength ratio are 0.70, 0.71, and 0.68, respectively, based on which this article establishes the finite element model for shale gas well X201. Then, the secondary development realizes the dynamic adjustment of the rock mechanical properties during the fracturing. The correctness of method and model in the article is verified through comparing the simulated calculation of casing deformation and the field multi-arm caliper logging data. The casing failure mechanism is revealed, providing a theoretical basis for the prevention of casing failure caused by shale gas fracturing.

Aimed at studying the casing wear in the highly deviated well drilling, the experimental study on the casing wear was carried out in the first place. According to the test data and the linear wear model based on the energy dissipation proposed by White and Dawson, the tool joint–casing wear coefficient was obtained. The finite element model for casing wear mechanism research was established using ABAQUS. The nodal movement of the contact surface was employed to simulate the evolution of the wear depth, exploiting the Umeshmotion user subroutine. In addition, the time-dependent geometry of the contact surfaces between the tool joint and casing was being updated continuously. Consequently, the contact area and contact pressure were changed continuously during the casing wear process, which gives a more realistic simulation. Based on the shapes of worn casing, the numerical simulation research was carried out to determine the remaining collapse strength. Then the change curve of the maximum casing wear depth with time was obtained. Besides, the relationship between the maximum wear depth and remaining collapse strength was established to predict the maximum wear depth and the remaining strength of the casing after a period of accumulative wear, providing a theoretical basis for the safety assessment of worn casing.