Column Pressure Research Articles

Design and application of well cementing technology based on the precise managed pressure balancing method in narrow pressure window hole sections

In the Sichuan Basin, the drilling of complex deep and ultradeep wells is restricted by the casing sequence. Multiple pressure systems are usually encountered in the same open hole section, and narrow safety density window is observed in vertical strata. The application of managed pressure drilling (MPD) technique which is often used in well drilling ensures the safe and efficient drilling, but it also brings about great challenges to the small-gap liner cementing at the lower part. Therefore, it is of great practical significance to research a cementing technology that can not only satisfy the quality requirement of small gap liner cementing, but also ensure the safe cementing in the strata with narrow safety density window. In this paper, a cementing technology based on precise managed pressure balancing method was proposed by referring to the successful application of MPD technique. According to the cementing design, the hydrostatic column pressure of annulus fluid is under-balanced (slightly lower than the formation pore pressure), and then a precise managed pressure drilling device is adopted to produce back pressure through wellhead restriction or apply wellhead compensation pressure, so that the balanced pore pressure can be reached in the process of cementing via the wellhead pressure and the flow friction of fluid in the annulus. After the cementing is completed, a certain compensation pressure is applied to the annulus continuously to prevent annulus channeling during waiting on cement caused by insufficient static pressure and slurry weight loss. After this technology was applied to an ultradeep exploration well in the Sichuan Basin, the qualification rate of borehole cementing quality reached 97%, and the well sections with good cementing quality accounted for 76%. In conclusion, this technology needs no additional equipment, and only by virtue of the MPD equipment, it can achieve safe cementing construction and cementing quality improvement under high displacement efficiency.

Design and Control of a Vapour Recompression C3 Splitter

Vapor recompression (VRC) based heat integration is usually employed for purifying a propylene-propane mixture in a C3 splitter. A fixed-speed drive (FSD) or a variable-speed drive (VSD) compressor may be employed for overhead vapor recompression. In this work, economic controllable designs for the two compressor types in a VRC C3 splitter are obtained via rigorous steady state and pressure driven closed loop dynamic simulations. Results indicate that for FSD compression, significant pressure drop must be provided across the compressor suction throttling valve for sufficient rangeability towards worst-case disturbance rejection. Accordingly, the column pressure and necessary compression ratio are higher for an overall more expensive process compared to a VSD compressor. The VSD compressor design corresponds to the lowest condenser temperature with water as coolant and the reboiler temperature driving force at the minimum constraint. In the FSD compressor design, the condenser temperature must be increased sufficiently above the minimum for an acceptable compression ratio. The case study highlights the importance for considering control at the conceptual design stage for designing a robust operable process.

Study on a Coupled Thermal–Hydraulic–Mechanical Model for Water Inrush from Collapse Column

A coupled thermal–hydraulic–mechanical (THM) model for water inrush from collapse column was carried out in this paper. An erosion equation was considered to simulate the mass loss in collapse column. Then the THM coupling equations and the erosion equation were solved in COMSOL to study the porosity, permeability, velocity, water pressure, temperature, and displacement change rule with time. Results indicate that the porosity, permeability, velocity, water pressure, and temperature increase with time due to the mass loss in collapse column, which show the evolution process of water inrush from collapse column. The increase of water pressure makes the displacement decrease with time. The increase of water pressure in collapse column also makes the pressure increase in coal seam floor, which can make the floor water inrush be more likely to occur.

The storm activities in the West Pacific from 1980 to 2018

The storm is an important weather system that significantly affects socioeconomics and human living. This study uses the global tropical cyclone best track data from IBTrACS, along with other meteorological states from ECMWF ERA-5 reanalysis from 1980 to 2018. In the West Pacific, storms are more likely to occur in summer (July, August and September). During the 39-year period, the occurrence of storm activities tends to be less frequent in summer, accompanied by increased sea surface temperature, total precipitation and total column water. It is also found that the storm number exhibited a high correlation with sea surface temperature, surface pressure, total precipitation and total column water in the middle West Pacific as well as the sea of Okhotsk in summer.

Separation of methanol-chloroform mixture using pressure-swing distillation: Modeling and optimization

The separation of methanol-chloroform mixture, a minimum-boiling azeotrope, is performed using pressure- swing distillation process via process simulation. In this study, the steady-state optimization was carried out using PRO/II with PROVISION v.10. The two different column configurations (low-to-high pressure and high-to-low pressure) were compared wherein the positions of the low-pressure column and high-pressure column were operated interchangeably to attain an optimized design. Additionally, different heat-integration configurations (partial heat- and full heat-integration) were applied to lessen the overall utility consumption. It was determined that the low-to-high pressure column configuration provided a more optimized result for all heat-integrated systems as compared to high-tolow pressure column configuration. Application of heat-integration further decreases the cooling water and steam consumption by 38.86% and 35.74%, respectively, for partial heat-integrated system, and by 44.58% and 41.01%, respectively, for full heat-integrated system.

Efficiency increase of sucker-rod pumps use

One of the factors decreasing the operation efficiency of wellhead pump unit is the fluid loss from the starting space between the pump, barrel coupling and the plunger. Due to the the pressure of liquid column rising within the barrel, as well as the friction wear over time, the space between the barrel-plunger pair increases, significantly amplifiying the fluid loss. The pressure within liquid columns on the inner and outer barrel surfaces should be aligned to prevent their widening due to the pressure. The space increases due to the hydrostatic pressure in the pumps in the upper parts of the barrel coupling, thus the fluid leakeage increases as well. In case, when the barrel coupling is in the lower part of cylinder, due to the pressure in the liquid column from within and outside, the space does not increase and as a result the well production rate rises for up to 3 %.

Evaluation of particle and bed integrity of aqueous size-exclusion columns packed with sub-2 µm particles operated at high pressure

The performance of columns packed with 1.7 µm particles for aqueous size-exclusion chromatography was assessed at high-pressure conditions and linked to particle- and column-bed integrity. Decreasing the particle size from 3.5 µm to 1.7 µm increases the resolution due to the improved mass-transfer characteristics, allowing to significantly speed-up analysis without compromising the selectivity. A sub-minute separation of intact proteins was realized on a 4.6 mm i.d × 75 mm long column packed with 1.7 µm SEC particles applying a flow rate of 1.8 mL/min, corresponding to a column pressure of 530 bar. Ultra-high pressure operation (exceeding manufacturer's recommendations) resulted in peak deformation, a shift towards earlier retention times, and an alteration in selectivity. To gain insights in the mechanisms of column deterioration, short 30 mm long columns were operated at UHPLC conditions, maximizing the pressure drop over individual particles. This resulted in the presence of fractured particles situated at the column outlet, as verified by scanning electron micrographs. Mercury-intrusion porosimetry and argon-adsorption measurements did not reveal significant differences in intraparticle volume between particle batches sampled before and after pressure stress testing. As particles at the column outlet fracture (but not collapse) at high pressure operation, a void was formed at the column inlet. The degradation of the separation performance appeared to be the result of a decrease in interparticle pore volume.

CFD simulation of dynamic heat transfer behaviors in super-long thermosyphons for shallow geothermal application

The use of super-long thermosyphons (TSs) is experimentally proved to allow a higher efficiency in extracting shallow geothermal energy. In this work, transient CFD (Computational Fluid Dynamic) simulation has been carried out for the super-long ammonia geothermal TSs, total length up to 54 m, in order to understand their heat transfer behaviors for thermal performance optimization. The results show that due to the influence of hydrostatic pressure of liquid column, boiling initially starts at the liquid pool surface and then gradually moves downward in start-up. With the initial liquid-column height higher than 10 m, the lower part of liquid pool in TSs would be throughout in quiescent state and make no contribution to heat extraction. At steady state, boiling zone in liquid pool shows a much higher heat transfer efficiency than that of partially-wetted area at the upper part of evaporator. Geothermal TS with 20% filling ratio of ammonia in evaporator, namely the initial liquid column height at 10 m, has the best thermal performance under the simulation test conditions. For super-long geothermal TSs (>50 m) using ammonia as working fluid, it is recommended to fill ammonia as much as possible, but the premise is that the initial height of liquid column must be controlled below 10 m.

A quantitative approach to investigate downpour condition of distillation column using gamma beam radiation

The area underneath the downcomer, part of distillation column is called the downpour area. If a tray deck troubleshoot like corrodes, it often first holes through in the downpour area. This will cause flooding due to the downcomer back up. An investigation of the crude distillation column was performed using an integrated system of photomultiplier detector and collimated gamma beam radiation. Gamma beam penetrated the object material as a transmitter of the radiation signal and will be accepted by the detector as its receiver. The main construction of this distillation column consists of 33 trays where each tray has two downpours and an accumulator. Distillation can be used to separate multi-component mixtures of crude oil. Many variables such as column pressure, temperature, size, and diameter are determined by the properties of the feed and the desired products. The measurement utilizes 75 mCi gamma activity and panoramic collimation design of the photomultiplier detector. This two equipment are aligned oppositely, and set on different four orientations scans, in order to obtain the condition of downpour system at each tray. Resolution scan of 5 cm each step from the bottom level to 34 m height. The duration time to measure radiation intensity is 3 seconds for each step. The quantitative result indicates abnormal flooding on the bottom segment tray #1 to #4. Abnormal condition is also identified as collapse tray, at tray #6. The quantitative approach has successfully determined the downpour condition in the distillation column.

Investigation of a single-pulse electrical arc discharge in vacuum based on the crater morphology and discharge channel

To improve the machining efficiency of electric machining, a novel method, called electro-arc machining (EAM), was put forward and obtains a great machining efficiency. Afterwards, many researches were conducted to investigate the machining mechanism of EAM; however, up to now, the behaviors of EAM in vacuum had not been studied yet. Therefore, in order to improve the EAM theoretical system, an investigation about the behaviors of single-pulse electro-arc discharge in a negative pressure environment was designed and conducted. The crater morphology, including discolored area diameter (Dh), molten area diameter (Dm), crater diameter (Dc), crater depth (h), white layer thickness, molten volume (Vm), removal volume (Vr), and removal volume ratio, was studied with different discharge current, discharge time, and vacuum degree. The regular characteristics of electro-arc discharge in a negative pressure environment were obtained, and the theoretical model of arc column pressure was improved.

Process Design and Steady State Simulation of Natural Gas Dehydration Using Triethylene Glycol (TEG) to Obtain The Optimum Total Annual Costs (TAC)

Natural gas is one of the most desired raw materials which can be used in petrochemical industries or as energy resource. Natural gas usually obtained from underground reservoirs and it must go through purification process so it can be utilized. All acid gas compounds such as H2S, CO2 and all liquids including H2O must be removed. Most industries use triethylene glycol (TEG) dehydration unit to absorb water from natural gas streams. Therefore, further research about design and optimization of dehydration unit using TEG should be conducted since the optimization of dehydration unit using TEG affects to safety, operability, and stability of the process. In this study, the optimization of TEG Dehydration Unit process is conducted to minimize the Total Annual Costs (TAC) and improve the efficiency of the process. Aspen Plus software is used to perform the simulation of TEG dehydration process. Optimization is conducted by changing several of the base case operating conditions which have been created using existing condition to obtain the optimum conditions with minimum TAC on the existing circumstances. The variables that are used in this research is absorber column pressure (35-45 barg with 2.5 barg interval) and lean TEG temperature (39-49°C with 2°C interval). The constrain of the absorber column pressure is less than 45 barg, since the natural gas feed pressure from well is 45.16 barg. The results show that by changing some operating conditions can reduce the size of the column, reduce the energy costs including steam, cooling water, and electricity costs. Therefore, it can reduce the TAC of the natural gas dehydration unit. The validation simulation results of the steady state of the TEG Dehydration Unit using Aspen Plus and the real plant produces relatively small % error, so it can be used to create a base case using the existing data. The mole fraction of H2O in dehydrated gas after optimization using Aspen Plus is 0.000178 while in real plant the result is 0.000200. The simulation results can reduce the TAC from 3, 416, 739 USD to 2, 973, 219 USD.

Improved understanding nanocomposite gel working mechanisms: From laboratory investigation to wellbore plugging application

Fluid loss is serious in low-pressure fractured reservoir. In this paper, the technique of wellbore isolation for temporary plugging is proposed to reduce the loss of workover fluid. Based on radical polymerization, the high-strength nanocomposite gel plugging agent was prepared by introducing nano-silica. Firstly, the strength properties of gel plug were studied through stress and strain evaluation, viscosity modulus test and wellbore sealing pressure evaluation, respectively. The working mechanism was revealed by infrared spectroscopy (FTIR), environmental scanning electron microscopy (ESEM) and differential scanning calorimetry (DSC) analysis. The study shows that under 50% compression strain, the compression capacity of the nanocomposite gel with 5% nano-silica is nearly three times higher than that of without adding nano-silica, and the thermal stability is improved by 38%, which has the potential to buffer the pressure of the liquid column in the bottom hole and perform good thermostability. Secondly, the actual wellbore simulation system confirmed its ability to seal the perforation zone. Result shows that the pressure-bearing gradient is 20 MPa/100m in the oil tube, and gel plug length can be designed according to the positive pressure demand. The addition of nano-silica makes the network of nanocomposite gel becoming denser, in favor to store more energy. The hydrogen bond generated in the nanocomposite gel increases its mechanical strength. Finally, the successful application of the nanocomposite gel for wellbore temporary plugging in a low-pressure carbonate gas well was summarized. This study provides an avenue to develop various nanocomposite gels for downhole jobs.

On factors affecting surface free energy of carbon black for reinforcing rubber

Abstract The surface activity of carbon black (CB) is an important factor affecting the reinforcement of rubber. The quantitative determination of the surface activity (surface free energy) of CB is of great significance. A simplified formula is obtained to determine the free energy of CB surface through theoretical analysis and mathematical derivation. The surface free energy for four kinds of industrial CBs were measured by inverse gas chromatography, and the influential factors were studied. The results showed that the aging time of the chromatographic column plays an important role in accurate measurement of the surface free energy of CB, in comparison with the influences from the inlet pressure and carrier gas flow rate of the chromatographic column filled with CB. Several kinds of industrial CB were treated at high temperature, and the surface free energy of CB had a significant increase. With the increase of surface free energy, the maximum torque was decreased significantly, the elongation at break tended to increase, the heat generation of vulcanizates was increased, and the wear resistance was decreased.

A model for calculating bottom-hole pressure from simple surface data in pumped wells

Bottom-hole flowing pressure and pump intake pressure (PIP) are important parameters to optimize the performance of oil wells. In recent years, downhole sensors are becoming widely used in electrical submersible pump systems to measure these pressures. However, it is still rare to use downhole sensors in sucker rod and progressive cavity pumped wells. In this study, two correlations were developed to calculate bottom-hole flowing pressure and PIP from readily available field data. The two correlations do not require measurements of buildup tests, but they rely on measuring the dynamic fluid level and estimating fluid gradient correction factor using either (1) the tubing gas flow rate or (2) the annular gas flow rate. Then, the PIP is calculated by the summation of either (1) the tubing pressure plus the tubing gaseous liquid column pressure or (2) the casing pressure, annular gas column pressure and the annular gaseous liquid column pressure. The correlations were developed using 419 field data points (389 points for training and 30 for testing) of wide range for each input parameter. Using the training data, the mean absolute percentage deviation (MAPD) between the calculated and measured PIPs is 25% and 20% for the first and second correlations, respectively. However, the testing data showed MAPD of 33% and 12% for the first and second correlations, respectively. The accuracy of these correlations is significantly higher than that of the previously available methods, and the correlations require simpler input. Such study is an original contribution to calculate the PIP with improved accuracy and without downhole pressures sensors.

Performance investigation of a new geothermal combined cooling, heating and power system

In this paper, a new geothermal combined cooling, heating and power system that integrates flash power cycle and ammonia-water absorption refrigeration cycle, is proposed to supply electricity, refrigerant water and domestic hot water simultaneously to users. In the system, the refrigeration cycle serves as the bottom cycle of the power cycle by further utilizing the exhausted geothermal water from the flasher of the power cycle, meanwhile all waste heat of the power and refrigeration cycles is recovered for supplying heat, thus effectively improving the energy conversion efficiency of whole system. This paper establishes detailed mathematical models of the proposed system and conducts a valid model validation. Then a preliminary design condition of the system is given and the results show that the exergy efficiency of system could reach 43.69% under the condition of 170 ℃ geothermal water. An exergy loss analysis is carried out based on the design condition, demonstrating that the maximal exergy destruction exists in the condenser of flash cycle, accounting for 48.53% of the total exergy destruction of the system; the components used for separating or mixing fluids including rectification column, absorber and flasher, occupying 17.68%, 9.02% and 9.30% respectively, are prone to generate exergy destructions. Finally a thermodynamic parameter analysis, in order to assess the effects of seven key parameters on the system performance, is performed. The results show that there are an optimal flash pressure (about 300 kPa) and an optimal generator temperature (about 120 ℃) respectively that could make the exergy efficiency of system maximal. Within some scopes, lower turbine back pressure and rectification column pressure, higher ammonia concentration of ammonia-strong solution, bring about higher exergy efficiency of system. Additionally the evaporation pressure and the reflux ratio of rectifier just make little difference on the exergy efficiency of system.

Two new phenolic glycosides with anti-complementary activity from the roots of Sanguisorba officinalis L

Sanguisorba officinalis L. is a traditional herbal plant that belongs to the genus Sanguisorba and the family Rosaceae. Two new phenolic glycosides (1–2), ten known phenolics (3–12), and six known monoterpenoid glycosides (13–18) were isolated from the roots of S. officinalis using silica gel column and preparative middle pressure liquid chromatography (MPLC). The chemical structures were elucidated based on extensive spectroscopic experiments, including 1D and 2D NMR as well as HR-ESI-MS, and comparison with those reported in the literature. Compounds 3–5, and 13 were isolated from the Rosaceae family and compound 7 was obtained from the genus Sanguisorba for the first time. Additionally, all compounds were evaluated for their anti-complementary activities against the classical pathway. Furthermore, compounds 1, 5, 9, and 14 showed significant anti-complementary activities with the 50% haemolytic inhibition concentrations (CH50) values of 0.40 ± 0.03, 0.57 ± 0.01, 0.51 ± 0.07, and 0.53 ± 0.05 mM, respectively.

Eco-efficient vapor recompression-assisted pressure-swing distillation process for the separation of a maximum-boiling azeotrope

The feasibility and effectiveness of the intensified vapor recompression-assisted pressure-swing distillation (PSDVRC) arrangements in different separation sequences are explored with separating a maximum-boiling methanol/diethylamine azeotrope as the specific example. The energy-efficient Heat Exchanger Network Synthesis (HENs) option is used to further improve the possible energy recovery in certain arrangement. The globally optimal arrangement is the intensified self-heat recuperative vapor recompression-assisted PSDVRC-FP-HEN process in the low-pressure column (LPC)-to-high pressure column (HPC) sequence. The reductions of 39.33% (13.93%) in total annual cost, 89.12% (81.95%) in carbon footprints, and the improvement of 116.31% (44.71%) in second-law efficiency can be achieved in comparison with the conventional process, wherein, the data in these brackets represent the economically optimal heat-integrated configuration. And the exergy destruction in each component (Sankey diagram) for all eco-efficiently intensified alternatives are obtained. Result shows that the exergy increase in LPC-to-HPC sequence is higher than that of another sequence, along with the major exergy losses generated in columns, and the distribution of the irreversibility for each individual component in the system is approximately identical when the entropy production analysis and exergy analysis are employed.

Application of comprehensive method in strengthening of a tall building

The concrete strength is low, which has a great influence on the compressive bearing capacity, column axial pressure ratio and column reinforcement. In order to solve such problems, it is often strengthened by increasing the section method. However, the use of increasing section method significantly affects the clearance of the building. So, it is strengthened by comprehensive method, in order to not significantly affect the clearance, that is using the outsourcing steel method and the increasing section method simultaneously. This method combines the advantages of the two most commonly methods, the increasing section method and the outsourcing steel method. The bearing capacity of the strengthened member is greatly improved, which not only reduces the influence of the increasing section method on the clearance, but also reduces the area of the externally-formed steel required. Since the adhesive is not required when pasting the steel, the durability of the strengthened member is improved.

Vapor Recompression C3 Splitter: Design and Control

Vapor recompression (VRC) based heat integration is usually employed for purifying a propylene-propane mixture in a C3 splitter. A fixed speed drive or a variable speed drive compressor may be employed for overhead vapor recompression. In this work, economic controllable designs for the two compressor types in a VRC C3 splitter are obtained via rigorous steady state and pressure driven closed loop dynamic simulations. A simple dual ended decentralized composition control system is shown to provide effective column regulation. The economic controllable design results indicate that when a fixed speed drive compressor is used, significant pressure drop must be provided across the compressor suction throttling valve for sufficient rangeability towards worst-case disturbance rejection. Accordingly, the column pressure and necessary compression ratio are higher for an overall more expensive process compared to a variable speed drive compressor. The case study highlights the importance for considering control at the conceptual design stage for designing a robust operable process.

Ambulatory venous pressure: new concepts

Background: The importance of the calf pump (the ‘peripheral heart’) in the lower limb venous circulation is well known. The ambulatory venous pressure (AMVP) is generally considered the quintessential functional test of calf pump function. However, much controversy exists on the basic hemodynamics of AMVP as well as its measurement. Recent work has helped to revise/clarify many of these controversies. Results from experimental simulations are used to illustrate key hemodynamic concepts. A multicameral model of calf pump Arnoldi popularized the notion that deep venous pressures can be monitored by inserting a needle in the dorsal foot vein (unicameral model). It has been shown recently that ambulatory venous pressures in the deep system is different from that in the dorsal foot vein and also the saphenous vein. AMVP profile in the three valved systems are different from each other (multicameral model). AMVP is traditionally monitored via % drop and also Venous refill time (VFT). Analysis of a large cohort of patients shows that VFT is more sensitive. % drop can be omitted as it is rare for it to be abnormal without concurrent abnormal VFT. AMVP is normal in venous obstruction, contradicting common belief. Ambulatory venous hypertension is a specific property of reflux, not obstruction. Supine venous pressure is elevated in obstruction but not reflux despite the suspected role of microvascular hypertension in reflux pathology. Role of calf capacitance & compliance: While severe reflux can shorten VFT, reduced calf capacitance and compliance are more important as can be shown in experimental set ups and clinical analysis. Calf Pump failure: Like the heart, the calf pump can eject all the inflow presented to it (up to 3X normal). Thus the popular concept of ‘calf pump failure’ from reflux overload has little concrete evidence to support it. Column segmentation: It is commonly assumed that valve closure results in column segmentation. It can be shown in experimental settings that collapse of the venous segment below the valve closure is necessary for column segmentation. Furthermore a reconstruction of the events surrounding column restoration makes it clear that a closed valve above the calf pump cannot reopen with the hydrostatic pressure of the restored column height below the closed valve alone. Much higher pressures generated by inflow interacting with wall tension of the infra-valvular segment is necessary to reopen the closed valve and restore flow. AMVP does not reach resting levels in experimental models till wall tension is restored to resting levels. A full blown reflux through an open valve will not transmit column pressure when the calf pump is partially collapsed. A non-invasive replacement for AMVP: Prevailing clinical practice and recent guidelines emphasize duration of reflux at the proximal saphenous, femoral and popliteal valves for assessment of reflux severity. It has been shown that these proximal valves play no significant role in column segmentation. A group of valves in the posterior tibial vein and the great saphenous vein near the ankle are the critical players in column interruption duration (CID). CID can be measured non-invasively by duplex after calf ejection by pressurized cuffs. Conclusion: AMVP has declined in clinical use as duplex identification of reflux in proximal valves has become common practice. More useful information can be obtained by using Duplex to measure CID.