CFD analysis on internal flow field of liquid level control valve under steady working state

Feb 2018 / by Chang Chen, Shiqiang Song, Jikun Guo, Qixin Zhang, Shifu Zhang and Tingao Shen

At present, all kinds of liquid level control system is widely used in ground and underground storage tanks and other containers, which plays an important role to ensure the safety of production. Thus, it become an indispensable device of modern oil production and storage. In this paper, the governing equations of the internal flow field of the automatic control valve are established by using the basic theory of computational dynamic fluid and the RNG two equations turbulence model. And, the internal flow field of the automatic control valve under steady working state is simulated by using Fluent CFD software. Then, the pressure diagram, velocity profiles figure, velocity vector diagrams were obtained. It is believed that the research results of this paper have reference value for the further optimization of liquid level control valve.
Keywords: Numerical research, internal flow field, liquid level control valve, steady working state

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Analytical model and numerical simulation on pipeline evacuation of offshore oil transportation system

Feb 2018 / by Chang Chen, Jikun Guo, Shifu Zhang, Qixin Zhang, Fan Zhang, Jianting Zhou and Ligang Zou

This paper focus on the pipeline evacuation of offshore oil transportation system. The mathematical model for pipeline evacuation was established, and the total emptying time under different working pressure was calculated by using MATLAB software. Frictional resistance and velocity distribution of the pipe under different time intervals was analyzed. The numerical simulation for the pipeline evacuation was carried out by using ANSYS software. The pressure distribution, velocity distribution and distribution law of the fluid trajectory are calculated and discussed, which can provide references for the analysis and control of the variation of the pipeline during the evacuation operation.
Keywords: Offshore oil transportation system; pipeline evacuation; numerical simulation; nnalytical model

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Numerical simulation of internal flow field of liquid level control valve during closing process

Feb 2018 / by Chang Chen, Qixin Zhang, Shiqiang Song, Shifu Zhang, Jikun Guo and Dongyu Yang

Liquid level control value is widely used in the process industry to control internal liquid height as pipe flow control component. During the operation of the liquid level control valve, the force condition of the value core directly affects the stability of the valve works. Therefore, it becomes the important factors in the design of the spring components of the liquid level control valve. In this paper, the internal flow field of the automatic control valve during closing process is simulated by using Fluent CFD software. The numerical simulation results show that in the process of closing the automatic control value, the water hammer phenomenon will be occurred at the beginning stage. With the continuation of the valve closing process, the pressure in upper chamber of the value core and internal chamber are rapidly reduced and tend to be gentle, while the pressure difference increases gradually. What is more, the flow of throttle gradually increases, and the inner chamber of the valve core appears small disturbance. These conclusions provide a theoretical basis for the technical design and improvement of the control valve.
Keywords: Numerical simulation, internal flow field, level control valve, closing process

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Application of fine interpretation technique of 3D seismic structure in Shen 150 block

Feb 2018 / by Chen He, Kaoping Song, Chi Dong and Jiwei Wang

The basic task of the development of seismic fine tectonic interpretation is the interaction analysis of threedimensional seismic data interpretation and real drill results, timely guide the well position adjustment and improve the success rate of drilling the reservoir. Aiming at the requirements of the development of the seismic geology task in the north Shen 150 area of the Rongshengbao sag, the technical combination suitable for the characteristics of this area has been worked out, and good geological effect has been achieved. First, the seismic data were evaluated. Second, the fine calibration was carried out. Third, the microstructure was studied. Finally, the concrete application of Shen 150 was studied. The results of 3D seismic fine structure interpretation is more truly reflect the shen 150 block of the underground structure in the study area of fault and the shape of the distribution situation, in order to improve the high steep complicated structure area drilling success ratio provides the reliable data.
Keywords: Three-dimensional seismic structure, microstructure, horizon calibration

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Theoretical research on steady-state and closing value characteristics of liquid level control value

Feb 2018 / by Chang Chen, Shiqiang Song, Shifu Zhang, Jikun Guo, Qixin Zhang and Jianyong Yang

During the refuelling process, the float switch closes when the internal tank liquid level reaches the highest level, but the automatic control valve cannot be closed simultaneously. If the delay time is too long, it may lead to an oil spill accident. In this paper, we analyzed the structure and basic working principle of the liquid level control. In addition, the flow of the automatic control valve, the force condition of the value core, the time required for closing the value, the speed and accelerated velocity of value core movement were theoretically studied according to the fluid momentum theorem and the kinematic equation of the valve closing process, which is of great practical significance for advancing research level of liquid level control valve.
Keywords: Theoretical research, steady-state, closing value characteristics, liquid level control value

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Polymer solution analysis experiment

Feb 2018 / by Lijia Song and Jiwei Wang

According to the practical demand of oilfield, instrumental analysis, physical simulation and reservoir engineering theory are applied for the experimental study on the influence of polymer concentration on the seepage characteristic of polymer solution, molecular coil dimension Dh and its distribution, oil displacement effect, besides, an analysis is made on the enhanced oil recovery mechanism by compound polymer flooding with broad relative molecular mass distribution. It turns out that for polymer with the same concentration, the resistance coefficient FR and residual resistance coefficient FRR decrease as core permeability increases; for the same core permeability, FR and FRR increase as polymer concentration increases. For polymer with broad relative molecular mass distribution compounded by 3 polymers (middle molecule, high molecule and ultrahigh molecule), with larger proportion of ultrahigh- molecule polymer, the molecular coil dimension Dh in compound polymer increases. The physical simulation indicates that while the polymer solution viscosity is identical, the flooding effect of compound polymer is better than that of high molecular polymer, and with increase of proportion of ultra-high-molecule polymer in compound polymer, the growth of recovery efficiency also increases.
Keywords: High concentration polymer flooding; resistance coefficient; residual resistance coefficient; molecular coil dimension; compound polymer

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Numerical research on flow characteristics of leaking liquid in interstitial space of double-wall oil tank

Feb 2018 / by Chang Chen, Shiqiang Song, Qixin Zhang, Shifu Zhang, Zhi Han, Jianting Zhou and Ligang Zou

The SF double-wall oil tank has an interstitial space with the thickness of 0.1 ~ 0.2 mm between the steel inner tank and FRP outer tank, and is equipped with a leak detection device to monitor the interstitial space for 24 hours. If internal structure of the interstitial space is designed unreasonably, the leaking liquid will be difficult to flow to the bottom of interstitial space, so that the leakage detection device cannot detect the leaking problem in time, leading to security risks during the operation process of double-wall oil tank. In this paper, the volume of fluid (VOF) model and the PISO algorithm are used to study the flow characteristics of the leaking liquid in interstitial space of double-wall oil tank based on FLUENT software. In order to reduce the computational complexity, the structure of the interstitial space of the SF double tank is simplified reasonably. It is believed that this research is valuable for the optimal design of the interstitial space structure of double-wall oil tank.
Keywords: Numerical simulation, flow characteristic, leaking liquid, interstitial space, double-wall oil tank

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Reservoir architecture of braided river and remaining oil distribution in YSM oilfield

Feb 2018 / by Li Xuewei and Fu Xiaoliang

As a case study, YSM oilfield has high water cut and high recovery factor. With various approaches, such as dynamic analysis, reservoir architecture study, simulation and well monitoring, the difference of seepage between planes, interlamination and interior layers can be evaluated, as well as the factors both from geological aspects, such as small structural high, updip sand pinch-out and fault sealing, and engineering aspects such as non-perforation, poor well status which impacted the formation and distribution of remaining oil. The research results suggest that the seepage flow difference is a critical geological factor for the formation and distribution of remaining oil. The vertical seepage to the upper inner differences make the remaining oil mainly distributed in the mid-upper sections of positive rhythm sands. And laterally, sand body splicing zone on plane and the marginal area of main sand body, normally the relatively low permeability area, the local micro tectonic highs and fault sealing affect the distribution of remaining oil in the oil spill area. The vertical distribution of remaining oil is affected by sedimentary rhythm, single sand bottom seriously flooded upper residual oil, residual oil in general oil sand top 1-2 meters. The coupling between geological factors, such as the scale and shape of the sand and the permeability difference between inter layers, and drilling factors such as well pattern design leads to uncompleted or inefficient injection and production pattern, which ends in a variety of remaining oil distribution patterns, such as the planar retention area, undeveloped reservoir and reservoirs with high pressure holding back.
Keywords: Braided river deposits, reservoir architecture, remaining oil, distribution disciplinarian, Da Gang oilfield

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Finite element analysis on deformation and stress distributions of double-wall oil tank under double supports installation mode

Feb 2018 / by Chang Chen, Shifu Zhang, Shiqiang Song, Qixin Zhang, Jikun Guo and Binbin Yu

The double-wall oil tank is more and more widely used in filling station due to the characteristics of corrosion protection, safety and economy. However, the outer tank of SF double oil tank has thinner wall thickness and lower strength, improper installation method may cause damage to the tank. In this paper, a simplified finite element model of double tank is established according to the structural characteristics of SF double-wall oil tank. Focusing on the 20 m3, 30 m3 and 50 m3 oil tanks which are widely used in the current gas stations, the deformation and stress distribution of the oil tanks under different bearing width and support position are calculated by ANSYS software respectively. Taking the 30 m3 oil tank as an example, the deformation, stress distribution characteristics and the influence of the bearing support position on the stress distribution are analyzed in detail, which would provide guidance for selecting the reasonable size and position of supporting bearing under double supports installation mode.
Keywords: Numerical simulation, stress distribution, double-wall oil tank, double supports installation mode

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Hydraulic fracture initiation and propagation of highly deviated well with oriented perforation completion technique

Feb 2018 / by Zhu Hai-yan, Deng Jin-gen, Chen Zhen-grong, Dong Guang, Li Ji-ran, Chen Zi-jian and Hu Lian-bo

In order to investigate the effect of different perforation angles (the angle between the perforation direction and the maximum horizontal principal stress which is also called the preferred fracture plane (PFP)) on the fracture initiation and propagation during the hydraulic fracturing of highly deviated well, laboratory experiments of the hydraulic fracturing of the BZ25-1 oilfield had been carried out on the basis of non-dimensional similar criteria by using 400mm3 cement cubes. We built the geometric model of the hydraulic fracturing fractures which considered the influences of the wellbore azimuth (the angle between the wellbore axis and the PFP), the perforation angle and the well deviation. The results showed that: the perforations in the PFP produce plane fracture; the fractures initiate from the perforations at the upper side of the well hole and then turn to the PFP when the perforation angle is 45°; when the well deviation angle and the perforation angle are both larger than 45°, the fracture initiates difficultly from the perforations at the lower side of the well hole, and multi-fractures easily initiate; when the perforation angle is 90°, multi-fractures initiate, such as twisting fracture, plane fracture, horizontal fracture and T-shape fracture, in addition, the fracture cannot initiate from the perforation tunnels; the larger the well deviation angle is, the easier is the multi-fractures initiation. Moreover, it is easier to result in micro-annulus which makes the fractures more complicated during the hydraulic fracturing of highly deviated well when the perforation angle is not along with the PFP. Oriented perforating technology should be applied in highly deviated well to obtain the big single plane fracture.
Keywords: Oriented perforating; highly deviated well; hydraulic fracturing; fracture initiation; fracture propagation

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