Optimization of anchorage support parameters for soft rock tunnel based on displacement control theory

In the construction of a soft rock tunnel,it is critical to accurately estimate the pre-stressed anchor support parameters for surrounding rock reinforcement;otherwise,engineering disasters may occur.This paper presents a support parameter selection method that aims to allow deformation as a control objective,which was applied to the tunnel located in Muzailing Highway,Min County,Dingxi City,Gansu Province,China.Through theoretical analysis,we have identified five factors that influence pre-stressing anchorages.The selection of mechanical parameters for the rock mass was carried out using an inverse analysis method.Compared with the measured data,the maximum displacement error of the numerical simulation results was only 0.07 m.The length of anchor cable,circumferential spacing of anchor cable,longitudinal spacing,and pre-stress index are adopted as the input parameters for the support vector machine neural network model based on particle swarm optimization(PSO-LSSVM).Besides,the vault subsidence and the maximum deformation of surrounding rock are considered as output values(performance indices).The goodness of fit between the predicted values and the simulated values exceeds 0.9.Finally,all support parameters within the acceptable deformation range are calculated.The optimal support variables are derived by considering the construction cost and duration.The field application results show that it is feasible to construct the sample database utilizing the numerical simulation approach by taking the displacement as the control target and using the neural network to specify the appropriate support parameters.

Performance Analysis of a Profile Control Agent for Waste Drilling Fluid Treatment

A method for the treatment of hazardous waste drilling fluids,potentially leading to environmental pollution,is considered.The waste drilling fluid is treated with an inorganic flocculant,an organic flocculant,and a pH regulator.The profile control agent consists of partially hydrolyzed polyacrylamide,formaldehyde,hexamethylenetetramine,resorcinol,phenol,and the treated waste drilling fluid itself.For a waste drilling fluid concentration of 2500 mg/L,the gelling time of the profile control agent is 25 h,and the gelling strength is 32,000 mPa.s.Compared with the profile control agent prepared by recirculated water under the same conditions,the present profile control agent displays better stability,salt-resistance,and performance.

Optimization of the Plugging Agent Dosage for High Temperature Salt Profile Control in Heavy Oil Reservoirs

After steam discharge in heavy oil reservoirs,the distribution of temperature,pressure,and permeability in different wells becomes irregular.Flow channels can easily be produced,which affect the sweep efficiency of the oil displacement.Previous studies have shown that the salting-out plugging method can effectively block these channels in high-temperature reservoirs,improve the suction profile,and increase oil production.In the present study,the optimal dosage of the plugging agent is determined taking into account connection transmissibility and inter-well volumes.Together with the connectivity model,a water flooding simulation model is introduced.Moreover,a non-gradient stochastic disturbance algorithm is used to obtain the optimal plugging agent dosage,which provides the basis for the high-temperature salting-out plugging agent adjustment in the field.

Optimization of Injection Parameters for Profile Control and Flooding in an Oilfield during High Water Cut Period

In order to improve the effect of water control and oil stabilization during high water cut period, a mathematical model of five point method well group was established with the high water cut well group of an Oilfield as the target area, the variation law of water cut and recovery factor of different injection parameters was analyzed, and the optimization research of injection parameters of polymer enhanced foam flooding was carried out. The results show that the higher the injection rate, the lower the water content curve, and the higher the oil recovery rate. As the foam defoamed when encountering oil, when the injection time was earlier than 80% of water cut, the later the injection time was, the better the oil displacement effect would be. When the injection time was later than 80% of water cut, the later the injection time was, the worse the oil displacement effect would be. The larger the injection volume, the lower the water content curve and the higher the recovery rate. After the injection volume exceeded 0.2 PV, the amplitude of changes in water content and recovery rate slowed down. The optimal injection parameters of profile control agent for high water content well group in Oilfield A were: injection rate of 15 m3/d, injection timing of 80% water content, and injection volume of 0.2 PV.

Research on Optimization Design of Deep Profile Control Injection Scheme in Block S

In view of the rapid decline rate of oil production and gradual increase of water cut in oil wells in Block S, based on the determination of the formula of foam profile control agent, the optimization study of foam profile control injection scheme was carried out. Petrel software is used to establish a facies controlled geological model based on stochastic modeling method in Block S, and CMG software is used for numerical simulation to design 7 sets of foam profile control prediction schemes. Dynamic data and numerical simulation methods are used to optimize foam injection mode and injection cycle. By simulating and calculating, the optimal injection method of alternating gas and liquid injection and the optimal plan with an injection period of 2 months were selected. Through the calculation results of various research plans, it can be seen that the water content of the optimal plan has decreased significantly, and the oil production rate has increased significantly, in order to slow down production decline, control water content rise, extend the economic recovery period of the oilfield, and achieve the goal of improving oil recovery.

Research on Mechanisms of Steam Breakthrough and Profile Control Design for Steam Soaking Well

Scaled physical model tests for steam breakthrough were conducted based on the analysis of mechanisms and influence factors of steam breakthrough. Physical simulation results showed that at the initial steam breakthrough, preferential flow channels were formed in narrow sand packs and most residual oil left in these channels was immobile. This shortened the steam breakthrough time of follow-up steam flooding and decreased the increment of oil recovery efficiency. Steam breakthrough occurred easily for a smaller producer-injector spacing, and a bigger difference in physical properties between fluids and rock. Steam breakthrough is more likely to occur at a larger formation permeability （k）, greater steam displacement velocity （u） and smaller producer-injector spacing （L）. Steam breakthrough time is a function of the parameter group （uk/L）, i.e. tb=3.2151 （uk/L）^-0.5142. A non piston-like displacement model was built based on steam breakthrough observation for a steam stimulated well in the Jinglou Oilfield, Henan Oilfield Company. The steam volume swept in different directions could be obtained from inter-well permeability capacity and breakthrough angle, and the steam swept pore volume （SSPV） was also determined. Numerical simulation showed that steam sweep efficiency reached its peak value when a slug of profile control agent （slug size 10%-15% SSPV） was set at one half of the inter-well spacing. Field test with 12.5% SSPV of profile control agents in the Jinglou Oilfield achieved success in sealing breakthrough channels and good production performance of adjacent producers.

DISPLACEMENT CONTROL AND KINETIC ANALYSIS OF A NOVEL VARIABLE DISPLACEMENT COMPRESSOR FOR AUTOMOTIVE AIR CONDITIONER

A novel variable displacement compressor (VDC) for automotive air conditioner (AAC) is introduced, which inherits the advantages of common wobble plate type VDC. It has fewer parts and makes less noise, and instead of pneumatic valve the displacement is controlled by electronic control valve. In order to know the control mechanism well and get a good control effect, a mathematical model for the variable displacement mechanism is developed according to the geometrical and kinematical information of the compressor. Using the model, the effect of relevant parameters on variable displace control is estimated. It is helpful to make the optimum decision in the flow control of AAC. As the novel displacement control device, the structure and control rule of electronic control valve is introduced. It can get better effect than the conventional pneumatic valves. And by using this new electronic control device, the optimum systemic control of AAC is available.

Production characteristics and displacement mechanisms of infilling polymer-surfactant-preformed particle gel flooding in post-polymer flooding reservoirs:A review of practice in Ng3 block of Gudao Oilfield

The pilot test of infilling polymer-surfactant-preformed particle gel(PPG)flooding has been successfully implemented after polymer flooding in Ng3 block of Gudao Oilfield in China.However,the production characteristics and displacement mechanisms are still unclear,which restricts its further popularization and application.Aiming at this problem,this paper firstly analyzes the production performance of the pilot test and proposed four response types according to the change of water cut curves,including W-type,U-type,V-type response,and no response.Furthermore,the underlying reasons of these four types are analyzed from the aspects of seepage resistance and sweep efficiency.The overall sweep efficiency of gradual-rising W-type,gradual-decreasing W-type,and early V-type response increases from 0.81 to 0.93,0.55 to 0.89,and 0.94 to 1,respectively.And the sum of seepage resistance along the connection line between production well and injection well for U-type and delayed V-type response increases from 0.0994 to 0.2425,and 0.0677 to 0.1654,respectively.Then,the remaining oil distribution after polymer flooding is summarized into four types on the basis of production and geological characteristics,namely disconnected remaining oil,streamline unswept remaining oil,rhythm remaining oil,and interlayer-controlled remaining oil.Furthermore,the main displacement mechanisms for each type are clarified based on the dimensionless seepage resistance and water absorption profile.Generally,improving connectivity by well pattern infilling is the most important for producing disconnected remaining oil.The synergistic effect of well pattern infilling and polymer-surfactant-PPG flooding increases the dimensionless seepage resistance of water channeling regions and forces the subsequent injected water to turn to regions with streamline unswept remaining oil.The improvement of the water absorption profile by polymer-surfactant-PPG flooding and separated layer water injection contributes to displacing rhythm remaining oil and interlayer-controlled remaining oil.Finally,the paper analyzes the relationships between the remaining oil distribution after polymer flooding and production characteristics of infilling polymer-surfactant-PPG flooding.The study helps to deepen the understanding of infilling polymer-surfactant-PPG flooding and has reference significance for more commercial implementations in the future.

Nonparametric Control Scheme for Monitoring Phase Ⅱ Nonlinear Profiles with Varied Argument Values

Profile monitoring is used to check the stability of the quality of a product over time when the product quality is best represented by a function at each time point.However,most previous monitoring approaches have not considered that the argument values may vary from profile to profile,which is common in practice.A novel nonparametric control scheme based on profile error is proposed for monitoring nonlinear profiles with varied argument values.The proposed scheme uses the metrics of profile error as the statistics to construct the control charts.More details about the design of this nonparametric scheme are also discussed.The monitoring performance of the combined control scheme is compared with that of alternative nonparametric methods via simulation.Simulation studies show that the combined scheme is effective in detecting parameter error and is sensitive to small shifts in the process.In addition,due to the properties of the charting statistics,the out-of-control signal can provide diagnostic information for the users.Finally,the implementation steps of the proposed monitoring scheme are given and applied for monitoring the blade manufacturing process.With the application in blade manufacturing of aircraft engines,the proposed nonparametric control scheme is effective,interpretable,and easy to apply.

PROFILE AND FLATNESS CONTROL SYSTEM IN 1700mm HOT STRIP MILLS OF ANSTEEL

Varying contact-length backup roll and linearly variable crown work roll are provided for improving the mill performance of profile and flatness control. Integrated with theses technologies, relevant profile and flatness control models are developed for hot strip mills on the basis of large amount of finite element calculation. These models include shape setup control model in process control system, bending force feedforward control model, crown feedback control model and flatness feedback control model in basis automation system. Such a profile and flatness control system with full functions is applied in 1 700 mm industrial hot strip mills of Ansteel. Large amount of production data shows that the crown precision with the tolerance of±18 μm is over 90%, the strip percentage which the actual flatness is within ±25 I-unit surpasses 96%, and general roll consume is reduced by 28% by using the profile and fiatness control system. In addition, schedule-free rolling is realized.

Researches on the PAM／Cr^3＋ Gel for Deep Profile Control

The profile control hard-gel is composed of polyarylamide (5-6g/L), whose molecular weight is 4,000,000 - 7,000,000 and hydrolysis degree is 17.6%, and cross-linking oxidation-reduction agent (Na2Cr2O7 + NH4Cl), with an delayed organic acid crosslinker which contains lactic acid/propionic acid/ethanoic acid and ethylene glycol. After research of the influence factors, such as pH, temperature, salinity and the dosage of delayed crosslinker, the optimum condition(pH 5.2, temperature 55℃, salinity < 7g/L) was found. Gelation time (12-144h) can be controlled by adjusting the dosage of the delayed crosslinker. Deep profile control experiments are carried out on heterogeneous models, which contains three serial high permeable and low permeable cores arranged in a parallel. After water flooding (total recovery, 24.3%), the first, second and third high-permeable cores each are sealed in turn by the profile control agent, and the total displacement recovery increases to 46.8%, 62.2% and 69.1% respectively. So, the greater the sealed depth, the larger the enhancing recovery will be. Finally, the oil displacement mechanisms of deep profile control are discussed.

The Synthesize and Property Evaluation of High Temperature Resistant Phenolic Resin-Type Profile Control Agent

Most of the mining method of domestic oilfield is waterflood development, thus the water content in the mid and late water flooding would rise faster, and the oil recovery rate would decline relatively more rapid. So it is very important to research profile control agent for stabilizing oil production resin-type profile control agent, and focus on researching the themal stability, shear resistance, gelation time and gelation strength and other properties of this profile control agent?[1]. Finally, the best ratio for synthesizing the high temperature resistant phenolic resin-type profile control agent was obtained.

Injection Scheme Optimization of Foam Profile Control on Block S103

Facing problems with oil production decreasing quickly and water content increasing gradually in S103 well area, the Foam Profile Control was studied on the basis of its confirmed agent formula. The facies-controlled geological model of S103 well area was generated using random model based on Petrel software and using numerical simulation based on CMG software. Gas liquid alternating injection pattern was optimized as the optimal solution through the simulation optimization. Two months are optimized as the optimal solution through the simulation optimization. The cumulative oil production is 0.933 × 107 kg which is higher than the value of subsequent water flooding and the other three. Finally, it reaches the goals of slowing down the production decline and controlling the water rising.

Preparation and performance of fluorescent polyacrylamide microspheres as a profile control and tracer agent

Polyacrylamide microspheres have been suc- cessfully used to reduce water production in reservoirs, but it is impossible to distinguish polyacrylamide microspheres from polyacrylamide that is used to enhance oil recovery and is already present in production fluids. In order to detect polyacrylamide microspheres in the reservoir pro- duced fluid, fluorescent polyacrylamide microspheres P（AM-BA-AMCO）, which fluoresce under ultraviolet irradiation, were synthesized via an inverse suspension polymerization. In order to keep the particle size distribu- tion in a narrow range, the synthesis conditions of the polymerization were studied, including the stirring speed and the concentrations of initiator, NaaCO3, and dispersant. The bonding characteristics of microspheres were deter- mined by Fourier transform infrared spectroscopy. The surface morphology of these microspheres was observed under ultraviolet irradiation with an inverse fluorescence microscope. A laboratory evaluation test showed that the fluorescent polymer microspheres had good water swelling capability, thus they had the ability to plug and migrate in a sand pack. The plugging rate was 99.8 % and the residual resistance coefficient was 800 after microsphere treatment in the sand pack. Furthermore, the fluorescent microspheres and their fragments were accurately detected under ultra- violet irradiation in the produced fluid, even though theyhad experienced extrusion and deformation in the sand pack.

Oil Production Optimization by Means of a Combined“Plugging,Profile Control,and Flooding”Treatment:Analysis of Results Obtained Using Computer Tomography and Nuclear Magnetic Resonance

Due to long-term water injection,often oilfields enter the so-called medium and high water cut stage,and it is difficult to achieve good oil recovery and water reduction through standard methods(single profile control and flooding measures).Therefore,in this study,a novel method based on“plugging,profile control,and flooding”being implemented at the same time is proposed.To assess the performances of this approach,physical simulations,computer tomography,and nuclear magnetic resonance are used.The results show that the combination of a gel plugging agent,a polymer microsphere flooding agent,and a high-efficiency oil displacement agent leads to better results in terms of oil recovery with respect to the situation in which these approaches are used separately(the oil recovery is increased by 15.37%).Computer tomography scan results show that with the combined approach,a larger sweep volume and higher oil washing efficiency are obtained.The remaining oil in the cluster form can be recovered in the middle and low permeability layer,increasing the proportion of the columnar and blind end states of the oil.The nuclear magnetic resonance test results show that the combined“plugging,profile control,and flooding”treatment can also be used to control more effectively the dominant channels of the high permeability layer and further expand the recovery degree of the remaining oil in the pores of different sizes in the middle and low permeability layers.However,for the low permeability layer(permeability difference of 20),the benefits in terms of oil recovery are limited.

VCR and ASR technology for profile and flatness control in hot strip mills

The roll contour pattern and variety of work and backup rolls in service and its effect on profile and flatness control performance in 1 700 mm hot strip mill at Wuhan Iron and Steel(Group) Corporation were tested and analyzed by the developed finite element models of different typical roll contours configurations.A rather smooth local work roll contour near strip edges and an increase in rolled length can be obtained by application of long stroke work roll shifting system with conventional work roll contours that is incapable of the crown control.In comparison with the conventional backup and work roll contours configuration,the crown control range by the roll bending force enhances by 12.79% and the roll gap stiffness increases by 25.26% with the developed asymmetry self-compensating work rolls(ASR) and varying contact backup rolls(VCR).A better strip profile and flatness quality,an increase in coil numbers within the rolling campaign and a significant alleviated effect of severe work roll wear contours on performance of edge drop control are achieved by the application of ASR with crown control and wear control ability in downstream stand F5 and VCR in all stands of 1 700 mm hot strip mill.

Study of Water Treatment Residue Used as a Profile Control Agent

A large amount of residue from the water treatment process has gradually accumulated and thus caused serious environmental pollution in waterflood oilfields. The water treatment residue is a grey suspension, with a density of 1.08 g/cm^3, and mainly contains over 65% of light CaCO3, MgCO3, CaSO4, Fe2S3 and Ca（OH）2. This paper ascertains the effect of water treatment residue on core permeability and its application in oilfields. Coreflooding tests in laboratory were conducted in two artificial cores and one natural core. Core changes were evaluated by cast model image analysis, mercury injection method and scanning electron microscopy （SEM）. Fresh water was injected into another natural core, which was plugged with water treatment residue, to determine the effective life. The results indicate that the water treatment residue has a strongly plugging capability, a resistance to erosion and a long effective life, and thus it can be used as a cheap raw material for profile control. In the past 8 years, a total of 60,164 m^3 of water treatment residue has been used for profile control of 151 well treatments, with a success ratio of 98% and an effective ratio of 83.2%. In the field tests, the profile control agent increased both starting pressure and injection pressure of injectors, and decreased the apparent water injectivity coefficient, significantly improving intake profiles and lengthening average service life of injectors. 28,381 tons of additional oil were recovered from these corresponding oil wells, with economic benefits of ￥3,069.55×10^4 （RMB） and a remarkable input-output ratio of 8.6：1.

Morphology and controlling factors of the longitudinal profile of gullies in the Yuanmou dry-hot valley

The morphology of the gully longitudinal profile(GLP) is an important topographic index of the gully bottom associated with the evolution of the gullies.This index can be used to predict the development trend and evaluate the eroded volumes and soil losses by gullying. To depict the morphology of GLP and understand its controlling factors, the Global Positioning System Real-time Kinematic(GPS RTK) and the total station were used to measure the detail points along the gully bottom of 122 gullies at six sites of the Yuanmou dry-hot Valley. Then, nine parameters including length(Lt), horizontal distance(Dh), height(H), vertical erosional area(A), vertical curvature(Cv), concavity(Ca), average gradient(Ga), gully length-gradient index(GL), normalized gully length-gradient index(Ngl), were calculated and mapped using CASS, Excel and SPSS.The results showed that this study area is dominated by slightly concave and medium gradient GLPs, and the lithology of most gullies is sandstone and siltstone.Although different types of GLPs appear at different sites, all parameters present a positively skewed distribution. There are relatively strong correlations between several parameters: namely Lt and H, Dh and H, Lt and A, Dh and A, H and GL. Most GLPs, except three, have a best fit of exponential functions with quasistraight shapes. Soil properties, vegetation coverage,piping erosion and topography are important factors to affect the GLP morphology. This study provides useful insight into the knowledge of GLP morphology and its influential factors that are of critical importance to prevent and control gully erosion.

Computing Open-Loop Optimal Control of the q-Profile in Ramp-Up Tokamak Plasmas Using the Minimal-Surface Theory

The q-profile control problem in the ramp-up phase of plasma discharges is consid- ered in this work. The magnetic diffusion partial differential equation （PDE） models the dynamics of the poloidal magnetic flux profile, which is used in this work to formulate a PDE-constrained op-timization problem under a quasi-static assumption. The minimum surface theory and constrained numeric optimization are then applied to achieve suboptimal solutions. Since the transient dy- namics is pre-given by the minimum surface theory, then this method can dramatically accelerate the solution process. In order to be robust under external uncertainties in real implementations, PID （proportional-integral-derivative） controllers are used to force the actuators to follow the computational input trajectories. It has the potential to implement in real-time for long time discharges by combining this method with the magnetic equilibrium update.

Nanoparticle stabilized emulsion with surface solidification for profile control in porous media

Profile control is utilized to redirect the injection water to low permeability region where a large amount of crude oil lies.Performed gel particles are the commonly used agent for redistributing water by blocking the pores in high permeability region.But the capability of deep penetration of performed gel particles is poor.Here,we formulate nanoparticle stabilized emulsion(NSE).The stability and the effect of NSE on the fluid redirection in a three-dimensional porous medium were investigated.By usingμ-PIV(particle image velocimetry),it was found that the velocity gradient of continuous fluid close to the nanoparticle stabilized droplets is much higher than that close to surfactant stabilized droplets.NSE behaves as solid particle in preferential seepage channels,which will decrease effectively the permeability,thereby redirecting the subsequent injection water.Furthermore,NSE shows high stability compared with emulsion stabilized by surfactant in static and dynamic tests.In addition,water flooding tests also confirm that the NSE can significantly reduce the permeability of porous media and redirect the fluid flow.Our results demonstrate NSE owns high potential to act as profile control agent in deep formation.