Gathering Pipeline Research Articles

Grey correlation analysis of the main influencing factors of wax deposition of waxy crude oil and determination of pigging period based on dynamic analysis

Normal temperature gathering and transportation has significant advantages in reducing energy consumption and cost. Due to the high wax content of crude oil in carbonate reservoirs, obvious wax deposition will occur in the process of gathering and transportation at room temperature. In this paper, according to the component analysis results of crude oil on site, the HEATANALOGY wax deposition model was used to calculate the wax deposition of different gathering pipelines. The main influencing factors of wax deposition were analyzed by grey correlation method. Finally, according to the pigging mechanical balance model, the safe pigging period is derived, and the relationship diagram of different pipe diameters, throughput and ground temperature is drawn. The results show that the wellhead temperature has the greatest influence on the initial wax deposition position and the peak wax deposition position of the pipe section. The flow rate has the greatest influence on the maximum wax deposition thickness of the tube wall. According to the relationship between the working conditions and the pigging cycle, it can be found that with the increase of the throughput, the pigging cycle decreases first and then increases. With the increase of ground temperature, the pigging cycle increases.

Testing the functionality of OLGA software for determining optimal oil transport modes to prevent solid particle deposition

Background: During operation, all mechanical impurities entering the collector through the flow lines settle at the bottom due to a decrease in flow velocity. This leads to a reduction in the capacity of the pipeline network, increased pressure, and premature equipment wear. To address this issue it is essential to understand the dynamics and intensity of sludge formation at the bottom of the pipeline. Aim: Evaluate the functionality and efficiency of the dynamic multiphase flow simulator in addressing challenges related to the transport of borehole fluid containing solid particles. Materials and methods: To build a mathematical simulation of multiphase flow with solid particles using OLGA specialised software, we selected one of the oil gathering lines in field N, with a diameter of 159х10 mm and a length of 1600 m, as the study object. This oil gathering line collects production from 16 wells. The OLGA simulator was used to model the process and measure flow parameters with different particle diameters, predicting the dynamics of variables such as time-varying flow velocities, fluid composition, temperatures, and particulate deposition. For a flow with a particle diameter of 104 µm, active precipitation occurs at flow rates between 200 and 300 m³/day. At flow rates of 400 m³/day and above, the velocity is sufficient to carry the particles without significant accumulation in the pipeline. Results: The software enabled the calculation of the dynamic system for different solid particle diameters in multiphase flow, addressing the challenge of evaluating the dynamics of solid phase accumulation in the pipeline and determining the fluid flow velocity required to prevent sludge formation. The software is suitable for implementing simulation modelling to develop technical solutions that minimise the risks of solid particle deposition in oil gathering pipelines during the operation of on-shore infrastructure facilities. Conclusion: The software enabled the calculation of the dynamic system for different solid particle diameters in multiphase flow, addressing the challenge of evaluating the dynamics of solid phase accumulation in the pipeline and determining the fluid flow velocity required to prevent sludge formation. The software is suitable for implementing simulation modelling to develop technical solutions that minimise the risks of solid particle deposition in oil gathering pipelines during the operation of on-shore infrastructure facilities.

Modeling of high-pressure transient gas-liquid flow in M-shaped jumpers of subsea gas production systems

Two-phase flow with low liquid loads is common in high-pressure natural gas offshore gathering and transmission pipelines. During gas production slowdowns or shutdowns, an accumulation of liquid in the lower sections of subsea pipelines may occur. This phenomenon is observed in jumpers that connect different units in deep-water subsea gas production facilities. The displacement of the accumulated liquid during production ramp-up induces temporal variations in pressure drop across the jumper and forces on its elbows, resulting in flow-induced vibrations (FIV) that pose potential risks to the structural integrity of the jumper. To bridge the gap between laboratory experiments and field conditions, transient 3D numerical simulations were conducted using the OpenFOAM software. These simulations facilitated the development of a mechanistic model to elucidate the factors contributing to increased pressure and forces during the liquid purging process. The study examined the influence of gas pressure level, pipe diameter, initially accumulated liquid amount, liquid properties, and gas mass flow rate on the transient pressure drop and the forces acting on the jumper's elbows. The critical gas production rate required for complete liquid removal of the accumulated liquid was determined, and scaling rules were proposed to predict the effects of gas pressure and pipe diameter on this critical value. The dominant frequencies of pressure and force fluctuations were identified, with low-pressure systems exhibiting frequencies associated with two-phase flow phenomena and high-pressure systems showing frequencies attributed to acoustic waves.

DEVELOPMENT OF AN EXPRESS ASSESSMENT OF THE RESULTS OF GEOLOGICAL AND TECHNICAL MEASURES TAKEN INTO ACCOUNT OF THE GATHERING SYSTEM

This article provides a rationale for the method of «express» assessment of changes in well flow rate when performing geological and technical measures in an oil field. In view of the cluster configuration of wells that is widespread in Western Siberia, the author identifies two groups of well pads, one of which is influencing, the other is reacting. At the influencing well clusters, as a result of the implementation of geological and technical measures to increase extraction from the productive formation, an increase in the produced fluid occurs. This leads to destabilization of the equilibrium in the “reservoir – well – pipeline” system. The consequence of a violation of this balance is an increase in the load on the reservoir fluid pumped in oil and gas gathering pipelines on individual branches of the field collection system. This leads to a redistribution of wellhead pressures at production wells, which, in turn, also leads to a change in bottomhole pressure and a change in well productivity. The author defines well pads where there is no increase in production, but where there is a change in pressure at the wellheads as reactive. With an increase in linear pressure on the pads, the energy balance in the operating production wells at the reacting well pads shifts towards a decrease in flow rate. Conversely, when wellhead pressure decreases, well productivity increases. These parameters will change until the energy balance of pressures in the wells is achieved. In connection with the above, within the framework of this work, an approach is presented for assessing changes in well operating parameters with increasing production in the field. An example of testing the proposed approach on a complex integrated model is given. To test this approach for adequacy, a comparison was made of theoretical calculations of changes in the operation of real wells with calculations performed on a customized complex integrated model of an oil field. It is worth noting that this type of calculation is characterized as approximate. Its use is advisable exclusively at the stage of preparing programs for performing geological and technical measures to determine reservoir zones in which the negative effect of increasing production will be minimal.

Dynamics Modeling and Analysis of Small-Diameter Pipeline Inspection Gauge during Passing Through Elbow

Abstract With small diameters, numerous elbows and complex internal environment, gathering and transportation pipelines are widely applied in the oil and gas pipeline network. To guarantee their safety, a pipeline inspection gauge (PIG) driven by the pressure differential is used. When the PIG collides with the elbows in the pipeline, it exhibits complex nonlinear dynamic behaviors and its reliability and stability may also be greatly affected. To study the vibration response characteristics passing through the elbow, the dynamic modeling of the small-diameter PIG is conducted first in this paper based on the ADAMS software. Then, the fluid-structure coupling is achieved by combining the dynamic model and the numerical calculation program of the fluid equation in Simulink. The simulation results indicate that the axial and swing acceleration amplitudes of the two sections increase with the increasing speed of the double-section detector, while the opposite trend is observed for the vertical acceleration amplitudes. By comparison, it is found that the acceleration response in the second section is generally greater than that in the first section. The results also show that the axial offset of the PIG at the elbow is inversely proportional to the speed and radius of the elbow, which is the main cause of the lift-off values of sensors.

Numerical simulation of sulfur particle agglomeration at bends of high sulfur natural gas gathering pipelines based on Euler–PBM coupling

Sulfur deposition can result in an increase in the wall thickness of high-sulfur natural gas gathering pipelines, leading to issues like unstable pipeline flow. It is crucial to reveal the aggregation of sulfur particles at key locations of high-sulfur natural gas gathering pipelines to predict the location and amount of sulfur deposition in the pipelines. In this paper, the Euler–PBM (Population balance model) coupling is used to establish a numerical simulation model of gas–solid two-phase pipe flow accompanied by sulfur particle agglomeration in the pipe bends, focusing on the influence of sulfur particle volume fraction, pipe inclination angle and inlet flow velocity on sulfur particles agglomeration behavior. The results show that the sulfur particles have a significant agglomeration effect at the bend of the collecting pipeline, and the agglomeration growth occurs to different degrees throughout the bend, and the main area of sulfur particles agglomeration is near the top wall of the pipeline, followed by other areas near the wall of the pipeline. When the inlet volume fraction of sulfur particles was increased from 0.05 to 0.25%, and the inclination angle of the pipe was increased from 30° to 90°, the distribution range of sulfur particle size after agglomeration became wider, and the maximum size of sulfur particles was 187.56 μm, and the effect of sulfur particle agglomeration was enhanced; the inlet flow rate was increased from 3.0 to 9.0 m/s, and the reduction range of sulfur particle size after agglomeration was 5.68–9.87 μm. The maximum particle size of sulfur particles also decreased, and the effect of sulfur particle agglomeration was weakened.

Research on Acid Aging and Damage Pattern Recognition of Glass Fiber-Reinforced Plastic Oil and Gas Gathering Pipelines Based on Acoustic Emission.

Pipelines extend thousands of kilometers to transport and distribute oil and gas. Given the challenges often faced with corrosion, fatigue, and other issues in steel pipes, the demand for glass fiber-reinforced plastic (GFRP) pipes is increasing in oil and gas gathering and transmission systems. However, the medium that is transported through these pipelines contains multiple acid gases such as CO2 and H2S, as well as ions including Cl-, Ca2+, Mg2+, SO42-, CO32-, and HCO3-. These substances can cause a series of problems, such as aging, debonding, delamination, and fracture. In this study, a series of aging damage experiments were conducted on V-shaped defect GFRP pipes with depths of 2 mm and 5 mm. The aging and failure of GFRP were studied under the combined effects of external force and acidic solution using acoustic emission (AE) techniques. It was found that the acidic aging solution promoted matrix damage, fiber/matrix desorption, and delamination damage in GFRP pipes over a short period. However, the overall aging effect was relatively weak. Based on the experimental data, the SSA-LSSVM algorithm was proposed and applied to the damage pattern recognition of GFRP. An average recognition rate of up to 90% was achieved, indicating that this method is highly suitable for analyzing AE signals related to GFRP damage.

Failure Analysis and Experiment of Shale Gas Gathering Pipeline

Failure Analysis and Experiment of Shale Gas Gathering Pipeline

Simulation of melting characteristics of thermal washing of the wax layer in the pipeline based on lattice Boltzmann method

ABSTRACT The escalation of transportation costs and the obstruction of pipelines due to wax deposition significantly impact the secure and efficient production of oil fields. The thermal washing method, characterized by its simplicity and cost-effectiveness, is widely employed for dewaxing crude oil gathering pipelines. The investigation of the melting mechanism of the wax layer during thermal washing is extremely important. In this paper, the two-zone composite model of multiphase flow-porous medium in the mushy zone is introduced into the solid-liquid phase change lattice Boltzmann model based on the enthalpy method, and the problem of circumferential inhomogeneity in the melting of the wax layer and the important influence of flow and heat transfer in the mushy zone on the thermal washing are systematically investigated. The demarcation point (γ tr) between the high and low liquid fraction zones is measured to be 0.81 by microscopic experiment. The impacts of varying γ tr and Ste numbers on wax melting at different circumferential locations are analyzed in detail. The results show that the melting efficiency of wax exhibits a nonlinear enhancement from − 90° to 90°. The melting efficiency of wax decreases with increasing γ tr for wax layers between 90° and − 45°. The melting efficiency of wax increases with higher Ste numbers at all angles. The Ste number increases from 0.42 to 5.0, and the melting efficiency of the wax layer at angles ranging from 90° to − 90° increases by factors of 2.16, 2.16, 2.20, 2.61, and 3.33 respectively. The growth of the Ste number improves the warming rate and shortens the generation time of convection at the center point of the wax layer. The research findings serve as a fundamental reference for formulating a rational and efficient thermal washing scheme.

A novel optimization model for tackling capacity challenges in natural gas gathering systems

In the layout optimization of natural gas gathering pipeline network, a lot of work has been done, but few scholars focus on the capacity optimization of gas gathering station (short for station). The structural relationship parameters of dendritic pipeline network and the flow parameters of pipeline network are complicated, which makes it difficult to establish the model, and at the same time, the existence of nonlinear term causes the difficulty of solving the problem. In the current two stage star-dendritic natural gas gathering pipeline network, pipeline sizes and station capacity are not well taken into account for the optimization of pipeline network layout at the same time. In this paper, a consideration station capacity and pipeline sizes: Two-stage star-dendritic network layout optimization model (SCPSTSDLO-Model) is constructed by integrating the factors of site discrete characteristics, station capacity and pipeline sizes, and considering the hydraulic pressure drop conditions of the network, and a solution framework based on the nonlinear processing is proposed, which can obtain the optimization results of optimal affiliation, station type, station site and pipeline sizes at the same time. Five cases are used to verify the validity and accuracy of the model and algorithm, compare the sensitivity analysis and solution algorithm, compare the hydraulic pressure drop conditions, and analyze the application in different forms of pipeline networks. The results show that the SCPSTSDLO-Model and the solution method established in this paper can obtain the optimal solutions under different topologies according to the application requirements, taking into account the capacity of stations and pipeline sizes.

Failure Causes Analysis of Circumferential Cracking on Gathering Pipeline in M Oil and Gas Field

The gathering and transportation pipeline experienced corrosion cracking failure after 2 years of operation. This paper conducted an analysis on the reasons for the pipeline failure by integrating background information on its usage, as well as observations, analyses, and detection of the morphology of failure samples. The results indicated that the fracture originated from the inner wall of the pipeline and extended to the outer wall along the wall thickness until complete fracture occurred. Based on microstructure analysis of the fracture and original microcracks at the top of the pipeline, it was determined that the fracture was a multi-source brittle fracture, spreading in both inter-granular and trans-granular forms with obvious radial quasi-cleavage fractures accompanied by secondary cracks. EDS analysis revealed that the element S was present in all zones related to fracture initiation, spreading, and transient zones. XRD analysis showed that corrosion products on the fracture surface were mainly composed of FeS, indicating the presence of H2S in the service environment leading to sulfide stress corrosion cracking characteristics in line with pipeline failure. It is recommended to confirm the source of H2S in the service medium and test residual stress within the same pipeline for potential risk assessment regarding cracking in other areas.

Simulation of Elbow Erosion of Gas–Liquid–Solid Three-Phase Shale Gas Gathering Pipeline Based on CFD-DEM

Shale gas gathering pipelines often contain liquid water and solid sand in the early stage of production, which leads to the failure of pipeline components easily under the action of gas–liquid–solid three phases. A computational fluid dynamics (CFD) model based on the fluid volume method (VOF) and discrete element method (DEM) was established to study the flow law of gas–liquid–solid three-phase flow in the elbow of shale gas gathering pipeline and the erosion law of the inner surface of the elbow was studied by coupling the Oka erosion prediction model. By comparing the experimental results of erosion damage of the elbow, it is found that the model established can well predict the erosion characteristics and erosion amount under the action of three phases. Combined with the field pipeline parameters and operating conditions, the paper further simulates the elbow erosion behavior under relevant working conditions. The results show that the particles rotate clockwise from the outer wall of the pipe through the bottom of the pipe when passing through the elbow under the action of gas and water phases. When the gas velocity increases, the particles at the elbow mainly gather at the bottom of the elbow and the wall of the outer arch. When the water content increases gradually, the particles gathered on the outer arch wall of the elbow move along the outer arch wall of the elbow and face the inner arch surface gradually, and the erosion area is mainly concentrated on the outer arch wall of the elbow and the outlet horizontal pipe. Under the condition of the liquid phase, the movement characteristics of the water phase and particles in the elbow of the gas gathering pipeline and the erosion characteristics of the pipeline surface are obviously different from those under the condition of the gas–solid two-phase. The model and simulation results established in this paper provide a reference for the erosion damage protection of shale gas gathering pipeline elbow.

Investigation into flow-induced internal corrosion direct assessment in small-diameter dry gas fluctuating pipeline

Small-diameter undulating natural gas pipelines with low gas transmission capacity do not have internal inspection conditions to grasp the internal corrosion status of the pipeline. This study focuses on a small-diameter undulating dry natural gas gathering and transportation pipeline, the internal corrosion mechanism of the pipeline is studied through corrosion products, and the specific location of the internal corrosion sensitive pipe segment is determined based on multiphase flow simulation and PMDT(pipeline non-contact magnetic anomaly detection); the excavation inspection is ultimately used to evaluate the internal status of the pipeline. The results demonstrate that the internal corrosion mechanism of ZL (ZI Lai) pipeline is O2 and CO2 synergistic corrosion in which O2 plays a dominant role, while the increasing flow rate will aggravate corrosion; The maximum general corrosion rate and critical inclination along the pipeline are 0.0218 mm/a and 18.4°, respectively. Furthermore, twelve corrosion sensitive segments have been identified, including two II-level and six III-level magnetic anomaly segments. The internal corrosion defects are localized at the 3–9o’clock position of the pipeline, with a maximum general corrosion rate not exceeding 0.0228 mm/a. Furthermore, the pipeline failure pressure of 12.27 MPa surpasses the maximum allowable working pressure of 8.84 MPa, ensuring its continued operational safety. The corrosion protection measures of reducing the water content of natural gas, adding vapor corrosion inhibitor and regularly detecting magnetic anomaly pipeline are developed.

Leak Detection for Natural Gas Gathering Pipelines Under Multiple Operating Conditions Using RP-1dConvLSTM-AE and Multimodel Decision

Leak Detection for Natural Gas Gathering Pipelines Under Multiple Operating Conditions Using RP-1dConvLSTM-AE and Multimodel Decision

Fast Detection of the Single Point Leakage in Branched Shale Gas Gathering and Transportation Pipeline Network with Condensate Water

The node pressure and flow rate along the shale gas flow process are analyzed according to the characteristics of the shale gas flow pipe network, and the non-leaking and leaking processes of the shale gas flow pipe network are modeled separately. The changes in pressure over time along each pipe segment in the network provide new ideas for identifying leaking pipe sections. This paper uses the logarithmic value of pressure as the basis for judging whether the flow pipe network is leaking or not, according to the process of varying flow parameters resulting in the regularity of leakage. A graph of the change in pressure of the pipe section after the leak compared to the pressure of the non-leaking section of pipe over time can be plotted, accurately identifying the specific section of pipe with the leak. The accuracy of this novel method is verified by the leakage section and statistical data of the shale gas pipeline network in situ used in this paper.

A self-supervised leak detection method for natural gas gathering pipelines considering unlabeled multi-class non-leak data

Detecting leaks in natural gas gathering pipelines is paramount for the safe and reliable operation of the gas and oil industry. Due to the lack of leak data and the changes in leak features, semi-supervised leak detection methods that use normal data for health model learning have attracted much attention. However, these approaches usually consider one-class normal samples as health data, which may fail to fit the reality of unlabeled multi-class non-leak data under variable operating conditions. In addition, existing semi-supervised methods often suffer from insufficient representation learning as they employ step-by-step training or rely on the low-level reconstruction of autoencoders. To address the above two key challenges, this paper proposes a novel end-to-end self-supervised leak detection method, self-supervised multi-sphere support vector data description. Specifically, it utilizes the presented multi-sphere support vector data description to model unlabeled multi-class non-leak data and the introduced self-supervised learning strategy to boost the representation learning of the end-to-end semi-supervised model. Moreover, the categories of unlabeled multi-class non-leak data are learned in an unsupervised way through alternating feature clustering and pseudo-label-based classification. A robust leak score calculation method is also designed to improve the performance of the proposed method. Finally, the experimental results on the field data collected from pipelines demonstrate the effectiveness of the proposed method.

Study of gas gathering pipelines hydraulic efficiency in gathering facilities of depleted fields

The study aims to investigate the hydraulic efficiency of gas-gathering pipelines of the Yuliivskyi oil and gas condensate production facility (OGCPF). Identify the main factors that lead to a decrease in the hydraulic efficiency of gas-gathering pipelines.

Investigating the dynamic characteristics of oil droplets spreading on solid surfaces in water

The use of thermoplastic-reinforced pipes for fluid recovery is becoming increasingly common because the oil field enters the high-water-cut stage in this process. Investigating frictional drag in case of oil-water flow in nonmetallic gathering pipelines is important because the dynamics of oil droplets on the inner surfaces of the pipes have a significantly influence on the drag. In this article, we experimentally and theoretically investigate the dynamic characteristics of the spreading of oil droplets with varying diameters from 600 to 900 μm and viscosities on surfaces with different degrees of wettability in water. The durations of oscillation and spreading of oil droplets on the surfaces submerged in water were found to be dependent on their diameter and viscosity. Because the prevalent equations used for calculations in this context cannot adequately describe the durations of oscillation and spreading of the oil droplets on surfaces in water, we corrected them based on experimental data. Finally, we examined the dimensionless maximum diameter of spreading of the oil droplets on the surfaces in water, and found that it was influenced by the diameter of the oil droplets and the wettability of the surface. We developed a theoretical model to represent the behavior of the oil droplets as they spread in order to predict the dimensionless maximum diameter of spreading, and verified it by using experimental data. And the results showed that the deviations between the experimental results and those of the model were generally within ±8%.

Experimental Evaluation of Anticorrosion of a Standard 20# Gathering Pipeline by Injecting Oxygen-Reduced Air into Simulated In-Service Wells.

Oxygen-reduced air flooding (ORAF) can effectively improve oil recovery in low-permeability reservoirs, but oxygen corrosion and CO2 corrosion in downstream gathering pipelines are inevitable due to the existence of oxygen, which limits the popularization and application of ORAF. In this paper, research on the corrosion inhibitor is carried out for the gathering pipeline of an oilfield with ORAF in China. Under the conditions of a simulated onsite gathering pipeline, 6 kinds of anti-CO2 corrosion inhibitors and 6 kinds of antioxygen corrosion inhibitors were selected to evaluate and screen the effects of 20# steel by the dynamic weight loss method. Two antioxygen corrosion inhibitors KY-12 and KY-17 and one anti-CO2 corrosion inhibitor A were selected for the experiment. The corrosion inhibition rates of the three inhibitors reached 83.67, 91.49, and 78.44%, respectively, at a temperature of 40 °C and an inhibitor concentration of 1000 mg/L. Through the experimental evaluation of three primary corrosion inhibitors at different temperatures (25, 40, and 55 °C) and different concentrations (400, 500, 800, 1000, and 2000 mg/L), the KY-17 corrosion inhibitor with the best stability at different temperatures was selected, and the corrosion inhibition effect was the best at different concentrations, with the highest slow release rate reaching 92.7%. This conclusion has a good reference significance for the selection and dosage of corrosion inhibitors for downstream gathering pipelines of the ORAF oilfield.

Analysis of sensitivity to hydrate blockage risk in natural gas gathering pipeline

During the operational process of natural gas gathering and transmission pipelines, the formation of hydrates is highly probable, leading to uncontrolled movement and aggregation of hydrates. The continuous migration and accumulation of hydrates further contribute to the obstruction of natural gas pipelines, resulting in production reduction, shutdowns, and pressure build-ups. Consequently, a cascade of risks is prone to occur. To address this issue, this study focuses on the operational process of natural gas gathering and transmission pipelines, where a comprehensive framework is established. This framework includes theoretical models for pipeline temperature distribution, pipeline pressure distribution, multiphase flow within the pipeline, hydrate blockage, and numerical solution methods. By analyzing the influence of inlet temperature, inlet pressure, and terminal pressure on hydrate formation within the pipeline, the sensitivity patterns of hydrate blockage risks are derived. The research indicates that reducing inlet pressure and terminal pressure could lead to a decreased maximum hydrate formation rate, potentially mitigating pipeline blockage during natural gas transportation. Furthermore, an increase in inlet temperature and terminal pressure, and a decrease in inlet pressure, results in a displacement of the most probable location for hydrate blockage towards the terminal station. However, it is crucial to note that operating under low-pressure conditions significantly elevates energy consumption within the gathering system, contradicting the operational goal of energy efficiency and reduction of energy consumption. Consequently, for high-pressure gathering pipelines, measures such as raising the inlet temperature or employing inhibitors, electrical heat tracing, and thermal insulation should be adopted to prevent hydrate formation during natural gas transportation. Moreover, considering abnormal conditions such as gas well production and pipeline network shutdowns, which could potentially trigger hydrate formation, the installation of methanol injection connectors remains necessary to ensure production safety.