Wenming Wang

Experimental study on axial load transfer behavior of a coiled tubing stuck in a marine riser

After years of using, the marine riser would need pigging operation to remove wax and other debris attached to its interior to recover production. Due to its low stiffness, coiled tubing would buckle when performing the marine riser pigging operation, which would make the injecting force not able to completely transfer into its end and finally damage coiled tubing and riser. Thus, in order to ensure the safety and reliability of the operation, this article reports an experimental study on this topic by building an indoor pipe-in-pipe platform. According to the experimental results, the inner pipe’s axial force transfer efficiency is always less than 1. When injecting force is less than the inner pipe’s critical helical buckling load, the inner pipe’s axial load transfer efficiency is basically the same under “unfixed boundary” and “fixed boundary” at the same force-out. When injecting force is bigger than the inner pipe’s critical helical buckling load, “unfixed boundary” would help decrease the inner pipe’s axial load transfer efficiency; when the injecting force is three times the critical helical buckling load, the inner pipe’s axial load transfer efficiency of “unfixed boundary” can be 3% smaller than that of “fixed boundary.” As the outer pipe of “unfixed boundary” would elongate, its axial load transfer would be “delay” compared with “fixed boundary,” which means injected displacement of “unfixed boundary” inner pipe would be bigger than those of “fixed boundary” at the same force-out. The research done above might provide important theoretical supports for the marine riser pigging operation.

Experimental study on axial load transfer behavior of a coiled tubing stuck in a steel catenary riser: At the stage of the coiled tubing un-helical buckled

Coiled tubing can be used for steel catenary riser pigging operations to remove wax and other debris attached on the interior of steel catenary riser to recover production and ensure safety. Due to its low rigidity, coiled tubing would deform which might finally damage coiled tubing and steel catenary riser. Thus, in order to ensure safety and reliability of the operation, this article proceeded experimental study on the axial load transfer behavior of a coiled tubing stuck in a steel catenary riser when the coiled tubing has not yet helical buckled. According to the experimental results, the inner pipe’s axial force transfer efficiency is always less than 1; the outer pipe of “unfixed steel catenary riser boundary” would elongate forced by the inner pipe within it, which makes the injected displacement of inner pipe within outer pipe of “unfixed steel catenary riser boundary” bigger than the injected displacement of inner pipe within outer pipe of “fixed steel catenary riser boundary” system at the same force-out; before the inner pipe helical buckles, inner pipe’s force transfer efficiency for unfixed and fixed system can be considered as the same. The research done above might provide important theoretical supports for the steel catenary riser pigging operation.

Vibration Analysis for Pigging of Suspension Pipe Bridge

Suspension pipe bridge is the key part of oil and gas pipeline system. Liquid loading during the pigging process will cause strong dynamic load of impact, thus the stability of structure will be destroyed. Paper establishes the pipeline pigging model suffered by the stress, analyzes the stress and vibration equation of the pigging pipeline. With the dynamic finite element simulation by the method of variable load, paper analyzes the vibration numeric of the pigging pipeline when the pig goes through the pipeline. The analysis of this paper provides the technical support and theoretical basis for pigging work.

Simulation analysis on load transfer of the marine pipe in pipe

Due to its unique character, Coiled tubing technology is widely used in various fields of marine oil and gas operations. But as the stiffness of coiled tubing is small, and the marine environment is complex, it is easy for the coiled tubing to destroy or cause an accident. Therefore we need to study axial load transfer characteristics of coiled tubing in the Marine riser to ensure safety and reliability of the operation. In this paper, through establishing the finite element model of coiled tubing down into of marine riser, axial load transfer law of unfixed boundary and fixed boundary coiled tubing was analyzed. Analysis results show that within fixed boundary condition, coiled tubing axial load transfer efficiency would be higher than that in unfixed boundary when the injection force is greater than the helical buckling critical load.

Synchronous clamping control of marine umbilical cable tensioner

The umbilical cable tensioner is a core component of deep-water oil and gas development, and it can lay and recover the umbilical cables to ensure the transmission of communication signals, electric signals or liquid injection. The displacements of tensioner’s clamping hydraulic cylinders, which are not synchronized as the nonlinear electro-hydraulic control system, results in the occurrence of the crawler mechanism’s stuck phenomenon or cause umbilical cable deformation or even cause damage by the extrusion in the umbilical cable’s clamping process. To ensure synchronous clamping, the structure scheme of umbilical cable tensioner, crawler mechanism, clamping mechanism and the hydraulic system of synchronous clamping control is designed in this study. This article also analyzes the function of structure parameters and hydraulic cylinders’ displacement, speed and acceleration, and builds the synchronous clamping mechanical model to reveal crawler mechanism’ clamping law. The study proposes the control strategy including the fast moving stage, the working stage and the pressuring stage based on proportional–integral–derivative control, and analyzes the characteristics of synchronous clamping control by building the synchronous clamping experimental platform in the lab environment. The experimental data shows that the tensioner’s hydraulic cylinders have excellent synchronous clamping performance and the theoretical analysis is feasible. The research has important guiding significance for the tensioner design, and provides theoretical support for the laying of the deep-sea umbilical cables.

Impact analysis of pigging in shield segment of gas pipe

The gas pipe in shield is one of the key parts of the long distance pipeline projects. It brings a great deal of uncertainty and risk factors for pipeline pigging operations. Paper establishes the finite element model, analyzes pig pigging and the impact over bending. Under the operating parameters of the pipeline pigging operations are given, paper develop the dynamic simulation model, analyzes the relationship among pipeline pressure, foam pigging speed and pipe stress. Through analyzing the motion law of acceleration and velocity, paper discusses the security of pipeline pigging operations.

Study on the mechanics of a coiled tubing within a marine ‘pipe-in-pipe’ system with a low diameter ratio

ABSTRACT To better understand the mechanics of coiled tubing working within the risers connected to Floating liquefied natural gas (FLNG), this paper studied a specific marine ‘pipe-in-pipe’ system with a low diameter ratio. The experimental results showed that the axial load on the inner pipe of an unfixed system increased with the increase in injected length. In this case, the ‘force-in’ was always larger than the ‘force-out’. The changing trend of force-in and force-out within the unfixed system was essentially found to be stable after a sinusoidal buckling of the inner pipe. Even though the magnitudes of force-in and force-out did not increase a lot, the injected length increased significantly. Relationship of force-in, as well as force-out, between fixed and unfixed system when the pipe was buckled sinusoidally and helically was found. The results help in working of a coiled tubing within small diameter marine risers.

Pose overshoot analysis of the marine spherical double plugging in twisting process

Marine spherical double plugging is a novel plugging device, which can achieve the initiative plugging in the oil and gas pipeline. In order to ensure that the plugging head will not collide with the pipeline wall and not be scratched by the drill cuttings, the analysis of twisting process is necessary to assure reliable operation. In this article, we designed the overall scheme of marine spherical double plugging and established the mathematic model of spherical double plugging. Through studying the twisting algorithm of plugging head and trajectory algorithm of plugging head contour, four dangerous points were obtained. The multi-body dynamic of the structure was built using ADAMS, and the twisting process and motion analysis of four points were analyzed. The twisting error of the plugging head between the four points and the inner wall of the pipeline was analyzed in overshoot states to obtain the maximum allowable overshoot of inserting hydraulic cylinder and twisting hydraulic cylinder. Simulation results show that overshoot of inserting hydraulic cylinder needs to be controlled within 11.5 mm and overshoot of twisting hydraulic cylinder needs to be controlled within 5.3 mm to avoid the unpredictable danger. This article will provide theoretical and technical support for the optimization design of control system and the plugging head.

Design of a new experimental coiled tubing injector

Coiled tubing (CT) injector is the key component of the CT equipment which is used to carry CT down into or out of the wellbore. So its performance will directly affect the success of the CT operations. This paper designed a new experimental CT injector, calculated its injection capacity when injecting CT with OD 38.1 mm and ID 32.9mm, designed and calculated its key components - sprocket chain and motor. Meanwhile, in order to make CT preferably pinched by the clamping block during the pressing process, finite element software was used to analysis the stress of CT. The results of the analysis show that when the V-shaped angle of the clamping block is 60°, the interaction between the clamping block and CT is optimal, the process of the clamping is smooth and the CT will not be hurt by the injector. The work of this paper would develop the theoretical basis for the manufacturing of CT injector.

The impact of pipeline bend on bi-directional pig and the theories for the optimal pig design

As a kind of pipeline robot, pig is needed to perform operations such as dewatering, cleaning and internal inspecting to improve the efficiency and ensure the safety of oil and gas pipeline. A pig with improper geometry will easily get stuck in the pipeline and the attached electrical equipments may also be damaged by the crash, especially when passing through pipeline bends or elbows. This is not only harmful for the pig itself, but also threatens the transportation security of pipeline. In this paper, avoiding getting stuck in the pipeline bend, the detail process when the bi-directional pig passing through pipeline bend is discussed. The proper method for determining the geometry size of the pig body is proposed and displacement of the bi-directional pig when passing the bend is presented after a force analysis of the sealing discs. The related theories for the pig design can provide some references to determine the size of pig body and make an appropriate setup of discs.