Drill Pipe Research Articles

Dynamic characteristic analysis of riser considering drilling pipe contact collision

As important equipment for deep-sea oil and gas development, risers are subjected not only to external ocean environmental loads but also to internal drilling pipe contact collisions. In this study, a dynamic analysis model of the riser system considering the contact collision of drill pipe in drilling operation is established. Moreover, the contact stiffness method is used to describe the contact collision force between the drill pipe and riser. The model is discretized using the finite element method and solved using the Newmark-β method. The dynamic characteristics of the riser under the action of the marine environment and drilling conditions are analyzed. In addition, the corresponding safety protection measures are put forward for the contact collision between the drill pipe and riser. The results show that the collision force between drill pipe and riser is the largest in the initial period, and the contact form is gradually stable. The distribution of the collision force is basically consistent with that of the bending moment, and the collision force and collision probability are the largest near the water surface and at the flexible joint of the bottom end, which is easy to cause column wear failure. The collision force and collision probability of the drill pipe and riser increase with the increase of platform offset and sea current velocity but decrease with the increase of top tension and bit pressure. The increase of the top tension and the increase of the platform offset will reduce the contact area between the drill pipe and the riser.

Study on Wear Resistance of Nickel Cladding Layer with Imitation Shell Convex Strip Structure on the Surface of 7075 Aluminum Alloy Drill Pipe

In this study, a nickel cladding layer with a bionic convex strip structure was applied to the surface of an aluminum alloy drill pipe, and laser cladding technology was used to improve the wear resistance of the aluminum alloy drill pipe. Firstly, by observing the morphological characteristics of the shell surface, the ratio of the width of the convex strips to the spacing between the convex strips was obtained as 0.39–0.53, and thus a model of the bionic structure was constructed. Numerical simulations were performed, and the results showed that the wear of the bionic structure was reduced by 77.6% compared with that of the smooth structure. Subsequently, the cladding layers of both structures were coated on the drill pipe using nickel powder as the material, and wear tests were performed. The microstructure, composition, and hardness behavior of the cladding layers were analyzed using scanning electron microscopy, an X-ray diffractometer, and a microhardness tester. It was found that the cladding layer mainly consists of Al3Ni2, and there is a transition layer between the cladding layer and the aluminum alloy matrix, whose hardness is lower than that of Al3Ni2. In addition, the groove space can be formed between the convex strips, which effectively reduces the frequency of the debris flow. The results of the wear tests show that the wear of the cladding layer with the bionic structure is reduced by 74.0%. Similar results in numerical simulations and experiments verified that the designed cladding layer with a bionic convex strip structure can significantly improve the wear resistance of aluminum alloy drill pipes.

Research on Cuttings Carrying Principle of New Aluminum Alloy Drill Pipe and Numerical Simulation Analysis

In order to improve the cuttings transport ability and well hole purification effect of horizontal shale gas wells in the Sichuan and Chongqing area, a new type of aluminum alloy drill pipe is put forward, and the floatability is validated by theoretical analysis and actual parameter calculation. According to the cuttings migration mechanism, the cuttings cleaning simulation model of the new aluminum alloy drill pipe and the traditional steel drill pipe was established by Fluent, and the hexahedral mesh is used to divide the model. Thus, the mesh independence and convergence of the two models are verified. Then, the simulation model is verified by comparing the calculation results of the two simulation models with the experimental data of the indoor cuttings migration device. Finally, the rock-cleaning ability of the two drill pipes is analyzed under the conditions of changing the cuttings particle size, well inclination angle, displacement, and mechanical speed. Compared with the traditional steel drill pipe, the new aluminum alloy drill pipe can improve the borehole purification capacity by 13% on average. This research result is of great significance in reducing the quality of cuttings in the annulus and improving the borehole purification effect.

Study on Directional Drilling Coupling Dynamics Based on Drill String Rotary Controller

Abstract In the process of long horizontal well in directional drilling, serious contact between drill string and wellbore leads to weight on bit loss. Therefore, this paper proposes a drill string rotary controller (DSC) for directional well, and its function test is completed through the experimental platform. Connected DSC working mechanism, a drill string coupling dynamic model is established under conditions of horizontal well in directional drilling. In the case study, the coupling dynamic characteristics of different units, including drill pipes and bottom-of-hole modules in axial and torsional directions, are studied. The results show that the effective value of drilling rate increases while the axial vibration velocity and amplitude of drill bit decreases. Moreover, in torsional direction, when drill string system is stable state, the rotating angular velocity of different drill pipes, rotary table, and collar is 31.16 rad/s, and the angular velocity of drill bit is 43.19 rad/s, respectively. It indicates the DSC working performance, which enhances the drilling system balance capacity. Overall, different from the sliding friction between wellbore and drill string, the addition of DSC realizes the separation and meshing of drill string and bottom hole modules, which can significantly increase the transition efficiency of weight on bit and torque value. Theoretical and experimental researches prove that the tool can effectively solve the problem of serious weight on bit loss in directional drilling process, and provides a new reference and idea for developing directional drilling technology when facing new challenges.

Research on Directional Hydraulic Coal Cutting and Outburst Prevention Technology in Soft and Hard Composite Coal Seams.

Affected by tectonics, soft and hard composite coal seams are widely distributed in China; the soft stratification in the soft and hard composite coal seam is the key to controlling the occurrence of coal and gas outburst accidents. Based on this, for soft and hard composite coal seams, in order to accurately extract soft layers, a directional hydraulic coal mining equipment has been developed, including a drilling rig pump truck system, a directional coal wireless measurement system, and a cutter drill pipe system. By constructing a mathematical model and conducting numerical simulations, it was found that the vertical stress, horizontal stress, and gas pressure of the coal body around the borehole after coal extraction decreased significantly compared to normal borehole conditions; the on-site test results indicate that the hydraulic coal extraction volume of directional hydraulic coal extraction boreholes reaches 0.25 m3 per meter. The total amount of coal extracted accounts for more than 3‰ of the total amount of coal within the coverage area. The average concentration of gas extraction in the coal extraction area is 80.15%, and the net amount of gas extraction from 100 m boreholes reaches 0.17 m3/(min·hm). After extraction, the measured residual gas content in the coal extraction and non-extraction areas decreased by 59.27 and 40.38%, respectively. Directional hydraulic coal mining technology can effectively solve the problem of coal and gas outburst prevention in soft and hard composite coal seams and has good application prospects.

Testing of a novel multi-branch horizontal well remediation technology for in situ remediation of contaminated soil and groundwater

Soil and groundwater contamination has become a key issue in urban redevelopment. It is particularly difficult to use heavy equipment for the remediation of restricted sites or areas contaminated by factories that are still in operation. In this case, horizontal wells are considered a potentially useful technology as they can potentially remediate contamination areas located below buildings and other surface/subsurface obstacles. This research first introduces the principles and advantages and disadvantages of direct push injection, improved slant well, high-pressure rotary jet technology, horizontal reactive media treatment wells, and horizontal directional drilling well. The key aspects for promising in-situ remediation techniques were summarized as remediation well design, remediation agent injection technology and drill pipe and well wall sealing technology. Based on the requirements for key technologies, a novel multi-branch horizontal well in-situ remediation process was proposed, which integrates vertical/horizontal directional drilling, rotary injection, and expansion sealing techniques, and relevant supporting drilling and injecting equipment were developed. A bench test and field test were conducted to test drilling tool performance, drilling accuracy, and injection radius of influence. The results showed that the developed supporting drilling tool met the process requirements and could complete multi-branch horizontal well remediation engineering construction. The deviation between the measured depth and the design depth of the multi-branch horizontal well constructed using this technology was less than 9%, and the deviation between the depth displayed by the guidance instrument and the measured depth was less than 1%. The injection radius of influence in the test field measured from the monitoring wells was greater than or equal to 5 m. The results of this research can provide an effective method for the remediation of contaminated sites.

Numerical Simulation of Hole Cleaning of a Horizontal Wellbore Model with Breakout Enlargement Section

Horizontal wells are more likely than vertical wells to have enlarged wellbore sections due to borehole instability. However, there is scarce research on borehole cleaning of horizontal wells with enlarged wellbore sections. In this paper, we establish a horizontal wellbore model with a breakout enlargement section using field borehole diameter data. We used the three-dimensional computational fluid dynamics (CFD) method and the Realizable k-ε turbulence model with the Euler–Euler approach to simulate the effects of the drilling fluid circulation return speed and the spinning speed of the drill pipe on the cutting movement of conventional horizontal wells and horizontal wells with a breakout enlargement section. The simulation results demonstrate that increasing the drilling fluid circulation return speed and the spinning speed of the drill pipe does not significantly improve the hole cleaning impact for horizontal wells with a breakout enlargement section. We analyzed the effects of the enlargement ratio, ellipticity, and principal axis orientation on the borehole cleaning effect of horizontal wells with a breakout enlargement section. The results show that the cleaning impact is better when the enlargement ratio is lower; moreover, the ellipticity is larger and the principal axis orientation is perpendicular to the gravity direction. This paper fills a gap in the existing theory of hole cleaning in horizontal wells and provides a theoretical basis for improving the hole cleaning effect in actual drilling processes.

Resonant Fatigue Tests on Drill Pipe Connections with Different Geometries and Sizes

In this study, a resonant bending fatigue test rig, designed and implemented by the University of Pisa, is presented, providing a detailed description of the set-up of the machine, the strain gauges calibrations, and the control system used with the main electronic devices. Several geometries of drill pipe connections and pipe samples made of different materials were tested, and all the obtained experimental fatigue results are presented in the paper and compared to previous experimental data. Fractographic images are provided to clearly show that, in two kinds of drill pipe connections, the crack initiation was found at the connection zone, whereas for another connection geometry, it was found at the pipe body. In order to interpret these latter results, a discussion about the section modulus of bending of the various sections of the drill pipes was provided, along with an FE model of a specific zone of one of these connections.

Design of Energy-efficient and Energy-efficient Slag Discharge Device for Large-bore Drilling Rigs

Micro pile hole is a kind of bored pile with a diameter of 100~400mm, which has been widely used in the field of transmission line engineering in recent years, and its hole formation usually uses DTH (Down-the-Hole) drilling rig. When DTH drilling rigs operate, the slag discharge method is to use the compressed air provided by the air compressor to blow the muck directly from the bottom of the hole to the ground. However, during the slag discharge process, it is difficult to blow out the muck due to the large cross-sectional area of the annular space between the hole wall and the drill pipe, especially after a certain drilling depth, and it is even more difficult to discharge if wet soil is encountered. Therefore, there is an urgent need to develop a machine for auxiliary slag discharge to improve the efficiency of slag discharge and reduce working energy consumption. In this paper, a barrel slag discharge device connected to the end of the drill pipe and following the drill bit to the bottom of the hole is designed, which can collect and store the rock slag that is difficult to discharge directly outside the hole, achieve a good slag discharge effect, and can reduce the energy consumption of the air compressor and reduce the drilling cost. Through the Fujian UHVDC transmission line project, the reliability and practicability of the barrel slag discharge device are verified.

CNPC, Sinopec Drill Ultra Deep in Search of Energy Security

_ China has spudded the country’s first ultradeep scientific exploration well exceeding 10,000-m depth as drilling began 30 May on CNPC’s Take-1 borehole in the Fuman oil field which is situated in the Taklamakan Desert of the Xinjiang Uygur autonomous region. CNPC (China National Petroleum Corp.) operates Fuman, which produced a third of Xinjiang’s Tarim Basin oil output in 2022, and aims to drill to a design depth of 11,100 m in record time using its own automated drilling rig equipped to cope with the extreme temperatures and pressures found in Northwest China, China state media reported. In its current Five-Year Plan, China aims to develop Fuman into a field capable of producing 35.7 million BOE annually by 2025. Fuman is the country’s largest ultradeep field and Tarim’s main crude oil production block, with reserves believed to exceed 71.5 billion bbl, according to CNPC. Journey to the Center of the Earth It took the Soviet Union 20 years to drill what is so far the world’s deepest well—the Kola Superdeep Borehole—which Russia sealed off and abandoned in 1992 after having reached a depth of 12,262 m (7.5 miles). There, drillers encountered 180°C (356°F) which deformed drill bits and pipes and made rocks so malleable they resembled plastic. CNPC expects its new automated, 82-m-high, 2,000-ton rig to penetrate 11,100 m of over 10 layers of continental strata in a record 457 days, reaching rock from the Cretaceous period that formed 66 million to 145 million years ago. China may be right to call its new drilling machine “the world’s first” automated rig capable of reaching 12,000 m considering details of its functionality. NOV built the Doyon 26, nicknamed “The Beast,” for Doyon Drilling to deploy on Alaska’s North Slope (Alpine field) under a long-term contract with ConocoPhillips, according to Tony Crawford, who worked nearly 2 decades in drilling and business development for Nabors in Alaska, Russia, and Kazakhstan, and in rig manufacturing for NOV in Russia and the US. With the help of the “The Beast,” Alpine was the first North Slope field developed exclusively with horizontal well technology, accessing 50 square miles of subsurface from a single drilling pad, according to ConocoPhillips. “It looks like the Chinese have created their ‘beast,’ have automated it, and added high-pressure and high-heat equipment,” said Crawford, who now owns Inerfuel, a Houston company that promotes nanO2 combustion catalyst to reduce carbon emissions in drilling. NOV’s “The Beast” is designed for extended-reach drilling and can reach a depth of 12,192 m, but with a drilling crew on board, he said. “Nabors has a robotic rig that is fully automated, called PACE-R801, but its maximum drilling depth is about 6,500 m. Drillmec has automated control systems, but not automated pipe handling and (other) equipment. “All the wells (where Doyon 26) is drilling are low to medium pressure, 5,000 psi or less, low to medium heat (50–80°C); nothing like China,” Crawford said of the North Slope. “The formations there are super soft; imagine drilling in clay mixed with sand.”

Increasing the fatigue strength of threaded joints of oil and gas equipment by plastic deformation of the thread under high load before make-up

Uneven distribution of stresses in the thread can cause fatigue failure of the joint, usually in the area of the first roots of the thread. This problem is very relevant for shouldered threaded joints of oil and gas equipment, which operate under conditions of significant cyclic loads. One of the ways to equalize the stresses in the thread is plastic deformation of the thread with a high load before make-up. The influence of various methods of such pre-deformation of the tool joint of drill pipes and the connection of sucker rods on the fatigue life in the thread roots of the pin and box has been studied. A method for optimizing the load for pre-deformation was proposed and it was found that the optimal load can increase the fatigue life by 5 times. The study was carried out by finite element analysis of the axisymmetric model in Abaqus/CAE and calculation of the fatigue life from the Brown-Miller dependence using fe-safe.

Loads Calculation and Strength Calculation of Landing String during Deepwater Drilling

As an important drilling tool, the landing string will be directly exposed to seawater during surface riserless drilling operations, and it will undergo complex deformation under the action of environmental loads such as ocean currents and waves and the displacement, heave and vibration of the drilling platform. At the same time, with the increase in water depth, the floating weight of drill pipe and casing also increases significantly, and the landing string will bear great tensile loads, which can easily cause accidents. Therefore, in this paper, based on ANSYS software, the finite element analysis models of three stages of the landing string lowering operation were established, and finite element simulations under different combinations of working conditions were carried out. Through theoretical analysis and numerical simulation, the ultimate load and stress distribution of the string under different operating sea conditions were obtained, and the external force requirements for restraining the lateral displacement of the string were proposed according to the existing standards of the industry. Thereby, the recommended safe operating time, safe operating conditions window and the required restraint reaction force of the support mechanism are given for landing string lowering operation throughout the year.

Drilling Pipe Corrosion Reduction Using Natural, Biodegradable, and Environmentally Friendly Additive to the Drilling Fluid

Corrosion is one of the disasters attacking the drilling tools, particularly the drill pipes. Drilling fluid is the corrosive that increase the rate of corrosion in the pipes. In this study, it is intended to reduce the corrosivity of drilling fluid using a Prosopis farcta powder material. A natural, biodegradable, and environmentally friendly additive is added to the fluid in different particle sizes and amounts to obtain the lowest corrosion rate. Experiments are conducted in a well-like environment (high pressure high temperature filter press) over a wide range of parameters including pressure, temperature, and properties of the drilling fluid under dynamic conditions. The aim is to eliminate or reduce the corrosivity of the mud as well as to control the losses. The results showed a lower corrosion rate, 0.0029 mm/year, using P. farcta material in comparison with those obtained by researchers in the previous studies.

Wear factors and mechanisms of L-80 steel casings

Casing wear in directional drilling is inevitable and may result in catastrophic failure of the casing column. It is thus essential to understand its mechanisms and quantify its extent by estimating the casing wear factor. In this research, actual field casing samples, drilling pipe joints and muds were considered. An in-house built testing facility was used to test several L-80 casing samples by considering three rotational speeds of the drill pipe tool joint (DP-TJ) (115, 154, and 207 rpm) and three side loads (1000 N, 1200 N and 1400 N). The influence of the water- and oil-based muds on the coefficient of friction, wear volume, wear factor and wear mechanisms were investigated. The results revealed that under water-based mud (WBM) lubrication casing wear volume and wear factors were more than twice that of oil-based mud (OBM) lubrication. Moreover, it was observed that as the side load increased under both OBM and WBM lubrication at a constant rpm, both wear volume and wear factor increased. However, increasing the rotational speed while maintaining the side load constant decreased the wear factor, owing to the localized softening effect caused by the high heat generation at the contact area and the possible hydrodynamic lubrication regime change at higher speeds. The analysis of the digital microscopic images taken at the wear region shows that abrasive mechanism was dominant in the case of OBM lubrication. On the other hand, both abrasive and adhesive wear mechanisms were present under WBM lubrication.

A Novel Method for Distinguishing Discontinuities In Ferromagnetic Materials Based On Eddy Current Testing Under Magnetization

Detecting inner- and outer-surface discontinuities of drill pipe is of great significance to the evaluation of the quality of the drill pipe. This paper proposes a method based on a magnetized eddy current testing technique to detect inner- and outer-surface discontinuities by analyzing the difference of the imaginary part signal characteristics of the receiving coil. For eddy current testing, the outer-surface discontinuities cause the local conductivity to be zero, while inner-surface discontinuities cause the perturbation of the magnetic permeability on the material surface. In this paper, the effects of conductivity distortion and permeability perturbation on induced eddy currents are analyzed by simulation. The conductivity distortion increases the magnetic field above the discontinuity compared to the magnetic field without the discontinuity, while the permeability perturbation reduces the magnetic field. Next, the difference in coil impedance can be used to distinguish the inner- and outer-surface discontinuities. Finally, the feasibility of the method is verified by experiments, and the results show that the inner- and outer-surface discontinuities can be discriminated.

RETURN OF ELECTRIC DRILLING — PROSPECTS FOR DOMESTIC TECHNOLOGY FOR HIGH-TECH WELL DRILLING

The article gives a comparative analysis of the results of electric drilling in the USSR and the advantages of the new electric drilling complex (EBK).
 Since 1948, over the next 15 years, the use of the first generation of EBK was organized in the fields of Azerbaijan, Turkmenistan, Bashkiria and Ukraine. The efficiency of mechanical drilling was higher than that of the turbine, but the overall performance was unstable due to a number of organizational and technical problems. The improvement of the ECB continued from 1963 to 1970: a series of geared electric boilers, equipment for directional drilling, a ground control and control station, and a data transmission system for a power electric cable were developed. The telemetry system provided the ability to control bottomhole equipment and monitor the drilling process.
 Bashkiria fields were the main "test site" for the development of the ECB, and this drilling method was used until 2013. Drilling performance in the complex geological and technical conditions of directional drilling was higher than the GZD drilling used everywhere in the USSR. In 2017, work began on the return of a new generation ECB to the well construction market in Russia. The new ECB meets modern requirements for the construction of high-tech wells through the use of a piercing valve motor (CVED) and a high-speed data transmission channel. The ECB provides optimal parameters of rock destruction regardless of the well profile and type of drilling agent, as well as increases the efficiency of prevention and elimination of complications and creates conditions for automation of the drilling process. In parallel with the development of ECBs on drill pipes with cable sections, electric drilling is being developed on a tubing — a promising method for drilling sidetracks and branches from horizontal boreholes. The level of readiness of the PU technology for the current day corresponds to SCT 3 according to State Standart R 58048-2017.

A fully coupled thermo-poro-elastic model predicting the stability of wellbore in deep-sea drilling. Part A: Analytic solutions

Wellbore stability is important to deep-sea drilling (DSD) for exploiting offshore oil and gas resources. Accurate prediction of the mechanical behaviors of rock formation around the wellbore can effectively prevent wellbore failure via adjusting mud weight. In this paper, a fully coupled thermo-poro-elastic (THM) model is developed by combining fluid circulation in the wellbore and rock deformation in the reservoir. Transient heat transfer in the wellbore/reservoir and heat exchange between the tubing, annulus, riser, casing, cement, seawater and rock formation are considered. By decomposing the problem into axisymmetric and antisymmetric sub-problems, the analytical solutions for transient temperature, pressure and stress in the rock formation and fluid temperature changes in the drill pipe, annulus and seawater near the riser are obtained and validated against with the numerical solutions, existing fluid circulation model, field measurement data and the existing model without considering fluid circulation. After that, a typical case study is carried out to show the mechanical behavior around the wellbore. It is found that the proposed fully coupled THM model has a high accuracy with a relative error of around 1.2%. There is a large difference in the predicted bottomhole temperature (BHT) and thus the temperature in the reservoir between the models with and without considering fluid circulation in the wellbore. An assumption of constant temperature boundary condition may lead to overestimated or underestimated results depending on the selection of the assigned wellbore temperature. In the DSD case studied, the rock formation at the upper part of the reservoir (Z < 0.40) is continuously heated and the rock formation at the lower part (Z > 0.6) of the reservoir is continuously cooled during fluid circulation, which thus results in a complex heat transfer and thus mechanical behavior in the wellbore/reservoir system, especially near the wellbore. The bottomhole temperature (BHT) decreases by 38.9 K due to cold fluid circulation from 3.68 min to 25.68 days, which can lead to 14.59 MPa tensile stress that cannot be ignored for wellbore stability analysis. The proposed analytical model provides a useful tool to predict the mechanical behaviors such as the transient temperature, pressure, displacement and stresses in the wellbore/reservoir system during fluid circulation in DSD. It runs efficiently in terms of seconds per case study in a portable laptop computer and can also work a benchmark for other numerical methods. However, the fully coupled THM model and its analytical solution are based on several assumptions, such as the heat generated by the drill bit rotation is ignored and only the liquid phase is considered, which requires further investigation.

Design of Flexible Drill Pipe with Ultra-Short Radius in Sidetrack Horizontal Well Based on the Snake Bone Directional Variability

Design of Flexible Drill Pipe with Ultra-Short Radius in Sidetrack Horizontal Well Based on the Snake Bone Directional Variability

Optimization of rotary friction welding parameters for dissimilar joints of exploration drill pipes

Optimization of rotary friction welding parameters for dissimilar joints of exploration drill pipes

Drill-Rep: Repetition counting for automatic shot hole depth recognition based on combined deep learning-based model

In order to solve the problems of low efficiency and dependability of human experience in shot hole depth recognition by manual interpretation of the massive drilling videos, this paper proposed a repetition counting framework from the perspective of representation object motion, and firstly studied and realized the automatic shot hole depth recognition by adopting the proposed framework by combining multiple deep learning-based models. Firstly, the periodic motion characteristics of the objects in the drilling video were analyzed, and the motion extraction model of the representative object was established based on YOLOv5 and Deep SORT algorithm to obtain the spatiotemporal sequence. Then, the sequence noise and redundant information were filtered according to the spatiotemporal relationship between the drill pipes and workers, to obtain a coherent, smooth, and clean motion sequence. On this basis, a drill pipe motion counting model was established by using the YOLOv5 network to detect the temporal boundary and repetition number of the drill pipe motion. Finally, combined with the pipe motion extraction model and counting model, the comprehensive reliable recognition method of shot hole depth was presented. The shot hole depth recognition trial was carried out on 1029 drilling videos from the Bureau of Geophysical Prospecting INC. The proposed method achieved 90.5% recognition accuracy (Acc) and 0.027 mean absolute error (MAE) with 64 frames per second (FPS) and 0.39 average recognition time ratio (Rt). Therefore, the proposed repetition counting framework solved the problem of efficient and intelligent drilling depth recognition of massive drilling videos and thus provided a new idea for repetition counting.