Lifting Method Research Articles

Optimal integrability for some integral system of Wolff type

In the paper, we obtain the optimal integrability for positive solutions of the following integral system involving Wolff potentials: {u(x) = W?,?(vq)(x); x ?, Rn, v(x) = W?,?(up)(x), x ? Rn, where p,q > 0,? > 0, ? > 1 and 0 < ?? < n. Ma, Chen and Li [Advances in Mathematics, 226(2011), 2676-2699] developed the regularity lifting method and obtained the optimal integrability for p > 1, q > 1. Here, based on some new observations, we overcome the difficulty there, and derive the optimal integrability for the case of p > 0,q > 0 and pq > 1. This integrability plays a key role in estimating the asymptotic behavior of positive solutions.

A numerical investigation on a capsule-intake of the electrical submersible pump in skid

The Electrical Submersible Pumping (ESP) system is one of the most commonly used artificial lift methods in the petroleum industry and one recent breakthrough in this system is enclosed in a capsule and positioned on the seabed in a skid. As it is a recent technology, with only a small amount of equipment currently in operation, there is a clear need for a greater understanding of the flow within this geometry with the objective of perfecting the design of this promising submarine boosting system. This paper presents a numerical investigation of single-phase flow within the scaled capsule-intake of an ESP system in the Skid considering a model with geometric and dynamic similarities in relation to a real equipment in operation in the Espadarte field, located in the Campos Basin, Brazil. The tridimensional and transient simulation for a case for one mass flow rate and inclination angles are investigated. While neglecting the effects of the diffuser and impeller in the system, the flow field features, axial and radial velocity profiles in the intake region were computed. The numerical results show that the flow in the intake region is dominated by the secondary flow, leading to the formation of bathtub vortex. It is expected that the vortices influence the flow pattern in the intake region, breaking the larger bubbles into smaller bubbles, making the transition from the slug flow pattern to the dispersed bubbles or bubbly pattern in which it would be more difficult to be dragged into the intake.

Combination of electrical submersible pump and gaslift for offshore wells in Vietnam

Artificial lifting systems have been in use for a long time all over the world. Artificial lifting systems act on the fluid column in the tubing to support and push the fluid column to the surface. Through the use of each method separately, we can analyze the advantages and disadvantages, the impacts and limitations of each method on the fluid column in the tubing, from which we can design an artificial lifting system to optimize production. In addition, practical limitations also have negative effects on the system such as injection pressure and injection gas available causing a restriction on the production when using GL, or pump horsepower and power supply causes limitations when using ESP. For those reasons, we can combine the two methods together to create an efficient production system. In this study paper, the effects on the fluid column in the tubing are analyzed when combining two methods, which are the GL method and the ESP method. Each method causes a different effect on the fluid column. That difference in this paper will be analyzed based on the "equivalent depth" method, which will represent the pressure points at each position in the tubing when using each artificial lifting method. In addition, we will use the "nodal analysis" method to find out the actual product of the production system when using a combination of the two methods. Based on the analysis of two methods "equivalent depth" and "nodal analysis", it has been proved that it is feasible and appropriate to combine the two methods GL and ESP for many special production wells that can be used for specific fields, such as deep wells. The systems of this combination can be used for wells for long time with respect to the pressure drop over time.

Bridging Factor and Sparse Models

Factor and sparse models are two widely used methods to impose a low-dimensional structure in high-dimension. They are seemingly mutually exclusive. In this paper, we propose a simple lifting method that combines the merits of these two models in a supervised learning methodology that allows to efficiently explore all the information in high-dimensional datasets. The method is based on a flexible model for panel data, called factor-augmented regression model with both observable, latent common factors, as well as idiosyncratic components as high-dimensional covariate variables. This model not only includes both factor regression and sparse regression as specific models but also significantly weakens the cross-sectional dependence and hence facilitates model selection and interpretability. The methodology consists of three steps. At each step, the remaining cross-section dependence can be inferred by a novel test for covariance structure in high-dimensions. We developed asymptotic theory for the factor-augmented sparse regression model and demonstrated the validity of the multiplier bootstrap for testing high-dimensional covariance structure. This is further extended to testing high-dimensional partial covariance structures. The theory and methods are further supported by an extensive simulation study and applications to the construction of a partial covariance network of the financial returns and a prediction exercise for a large panel of macroeconomic time series from FRED-MD database.

Significant production improvement using optimization of completion and artificial lift: case studies from South-West Iran

Productivity of wells in South-West Iran has decreased due to completion and production problems in recent decades. This is a large risk against sustainable production from the fields. To allow stable production, an important measure is completion and production optimization including artificial lift methods. This was investigated using simulations validated by pilot field tests. Several case studies were considered in terms of their completion and production. Five scenarios were investigated: natural production through annulus and tubing (scenario-1 and 2), artificial gas lift production through annulus (scenario-3), through tubing using non-standard gas lift (scenario-4) and using standard gas lift (scenario-5). Scenario-1 is currently the case in most wells of the field. To find the optimal scenario and completion/production parameters, simulations of 11 wells of an oilfield in the region were carried out using nodal and sensitivity analysis. The optimized parameters include wellhead pressures (WHPs), tubing dimensions, maximum tolerable water cuts and gas oil ratios and artificial gas injection rate. Simulation results were validated by pilot field tests. In addition, appropriately selected wellhead and Christmas trees for all scenarios were depicted. Simulations confirmed by field pilot tests showed that optimization of completion and production mode and parameters can contribute largely to production improvement. The results showed that the current scenario-1 is the worst of all. However, production through tubing (scenario-2) is optimal for wells which can produce with natural reservoir pressure, with an increase of 800 STB/Day rate per well compared with scenario-1. However, for wells requiring artificial gas lift, the average production rate increase (per well) from the annulus to tubing production was 1185 STB/Day. Next, using the standard gas lift (scenario-5) was found to be the optimal mode of gas lifting and is strongly recommended. WHPs in scenario-5 were the greatest of all, whereas scenario-1 gave the lowest WHPs. The optimal tubing diameter and length were determined. The greatest maximum tolerable water cut was obtained using scenario-5, whereas the lowest was with scenario-1. The maximum tolerable GOR was around 1900 scf/STB. Changing of scenarios did not have significant effect on maximum tolerable GOR. The optimal artificial gas injection rates were found. This validated simulation work proved that completion and production optimization of mode and parameters had considerable contribution to production improvement in South-West Iran. This sequential comprehensive work can be applied in any other field or region.

Modeling the performance of progressive cavity pump under downhole conditions

Progressive Cavity Pump (PCP) is a common artificial lift method for high viscosity liquid production. In elastomeric stator PCP, the clearance between the metal rotor and elastomeric stator prevents mechanical friction but also causes reverse flows phenomenon known as slippage. This clearance is a key parameter in modeling pump performance. Currently, existing PCP slippage models are developed for single-lobe, constant clearance, at surface operation. This study experimentally and theoretically investigates the effect of downhole condition on behaviors of elastomeric stator. An analytical model for stator deformation based on Hooke's Law and composite cylinder theory is proposed. The proposed model is coupled with a developed analytical model for PCP performance at surface conditions to introduce, for the first time, a comprehensive model applicable for multilobe PCP operating at downhole conditions. The coupled model is validated against experimental data of PCP characteristic curves for different stator materials. Using the model, sensitivity analysis of design parameters (initial pump clearance, stator thickness, material stiffness, number of lobes) on pump performance is carried out. The findings of this study can aid manufacturers and operators in optimizing PCP design and operation.

Influence of tubing/oil-blanket lifting on construction and geometries of two-well-horizontal salt caverns

Underground TWH (Two-well-horizontal) salt caverns are an ideal storage medium for large-scale energy storage, having large usable volumes and high construction efficiency. Different tubing/oil-blanket lifting techniques relate to different solution mining rates and help define cavern geometries based on the previous experience of SWV (Single-well-vertical)-cavern construction. In this study, we present a complete and comprehensive evaluation of the influence of a particular tubing/oil-blanket lifting method on TWH-cavern leaching and geometric shapes. Based on the solution mining numerical simulation original program TWHSMC V2.0 (Two-well-horizontal solution mining cavern V2.0), we carried out a set of numerical simulations, such that the cavern construction process is real-time display and easily recorded. The results demonstrate that with a matching water injection rate, the outlet brine concentration is not sensitive to tubing/oil-blanket lifting. During construction of a horizontal cavern with a volume of 300,000 m3, lifting tubing on both sides simultaneously yields the shortest leaching time (near 307 days). Only lift the tubing on one side will form an asymmetrical cavern, with the height of the cavity near the side being higher than on the opposite side. The lower the frequency of tubing and oil blanket lifting, the smaller the height/length ratio coefficient is, meaning the cavern is closer to the horizontal. Therefore, when constructing TWH-caverns in thinly-bedded rocksalt formations, simultaneously lifting the both sides of tubing and oil-blanket, in addition to a lower lifting rate, are required. This research provides theoretical basis and engineering guidance for TWH-cavern constructing in thinly bedded rocksalt formations.

Effect of the gas injection angle and configuration in the efficiency of gas lift

In oil wells using gas lift as a method of artificial lift, the gas is normally injected inside the tubing at a downward direction, i.e., in countercurrent flow relative to the fluids coming from the reservoir. This creates turbulence in the flow, causing pressure drop for the gas to change direction and to flow upward along with the produced fluid. The optimization of this geometry, by changing the gas injection angle, for instance, may introduce some gain. In this paper, we present theoretical analyzes and computer simulation showing that, for high gas injection flow rates and/or small jet diameters, it is possible to obtain a gain when reversing the direction of the gas injection. Although it is intuitive that an upward injection can improve the flow, experiments are needed to give confidence to this proposal. However, there is very few studies in the literature addressing this issue. To improve the knowledge of subject, this study shows experiments performed using an experimental well flowing oil and natural gas. Such an experiment, at real scale configurations and fluids is unique. The usual configuration, injecting downward, was compared with two alternatives, injecting the gas jet upward and injecting in an annular pattern. This article describes and discusses the tests and the results obtained. Although the tests have not been performed with the ideal conditions to maximize the gain, the results were consistent and conclusive. A slight local gain was observed due to the gas angle change, consistent with the previsions of a simple theoretical model. The estimated gains can reach 2 bar and are obtained at no additional cost by simply inverting the gas jet direction, but it is more effective for wells with high gas injection flow rate. Since gas lift is applied to a large number of wells, even a modest gain can be significant in the overall context. Based on the results, it is speculated that there is probably an optimum way to inject gas by taking advantage of the jet inversion and of the reduction on slippage between gas and liquid.

Evaluation of Artificial Lift Methods to Increase Oil Production from Depleting Oil Wells in Gulf of Mexico

This paper summarizes the research work with reference to artificial lift methods to increase oil production form mature oil wells in Gulf of Mexico. 
 Increase oil production or oil recovery from oil reservoirs is very important. If the average worldwide recovery factor from hydrocarbon reservoirs can be increased beyond current limits, it will alleviate a number of issues related to global energy supply. Currently the daily oil production comes from mature or maturing oil fields and reserves replacement is not keeping pace with the growing energy demand. 
 This paper presents big picture overview of artificial lift methods for mature oil wells in Gulf of Mexico.

Optimisation of Artificial Lifts Using Prosper Nodal Analysis for BARBRA-1 Well in Niger Delta

Hydrocarbon exploration basically requires effective drilling and efficient overpowering of frictional and viscosity forces. Normally, frictional power losses occur in deep well systems and it is essential to analyse each component of any well system to determine where exactly pressure is lost, and this can be done using Nodal Analysis. In this study, nodal analysis has been carried out with the use of PROSPER, a software for well performance, design and optimisation. Artificial lifts can then be used to solve the problem of frictional power losses. To increase the production of Barbra 1 well in the Niger Delta and hence extend its functional life, we have applied nodal analysis. Modelling results for three artificial lift methods; continuous gas lift, intermittent gas lift and electrical submersible pump were found to be 1734.93 bbl/day, 451.50 bbl/day and 2869 bbl/day respectively. The output from the well performance without artificial lift was 1370.99 bbl/day by applying Darcy’s model. Meanwhile, the output from the well without artificial lift is 89.90 bbl/day when aided with productivity index (PI) entry, the normal model for intermittent gas lift. Hence, from the comparative analysis of the results obtained from this study, it was deduced that when artificial lifts are employed, the well output increases significantly from 1370.99bbl/day to 2869 bbl/day (electrical submersible pump). This study concludes that wells such as Barbra 1 are good candidates for artificial lift, and this is evidenced by increasing productivity.
 Keywords: Production optimisation, nodal analysis, prosper simulator and barbra well.

A comparison of three shoe sole impression lifting methods at high substrate temperatures.

Footwear impressions are a common form of evidence found at crime scenes, and the accurate recovery and recording of such impressions is critical for shoe sole comparison and identification. The lifting of shoe sole impressions from hot surfaces (>30°C/86°F) and in hot environments has received little attention in the literature, particularly in relation to the recovery of class and randomly acquired characteristics (RACs) required for accurate comparisons. This study addressed this knowledge gap by comparing the performance of three common impression lifters (gelatin, adhesive, and vinyl static cling film) at recovering shoe sole impressions in dust from hot flooring substrates. Dry origin dust shoe sole impressions were made on ceramic tile, galvanized metal, and laminated wood flooring using a shoe that possessed two RACs and five class characteristics present on the sole. Substrates were left in direct full sun for five hours during a summer day prior to lifting. Performance was measured by the proportion of RACs and class characteristics visible in each lifted impression. Results demonstrated that the vinyl static cling film tested performed poorly across all substrates, particularly for metal (23.8% marks recovered), including notable shrinkage of the lifted impression. In contrast, adhesive (~96% marks recovered over all substrates), and to a lesser extent gelatin (~85%), lifts were highly successful on hot substrates. These data suggest that adhesive lifts can consistently and accurately recover shoe sole impressions from hot substrates. This study contributes critical information for crime scene examiners to improve and expand evidence recovery in hot environments.

Quantum function algebras from finite-dimensional Nichols algebras

We describe how to find quantum determinants and antipode formulas from braided vector spaces using the FRT-construction and finite-dimensional Nichols algebras. It improves the construction of quantum function algebras using quantum grassmanian algebras. Given a finite-dimensional Nichols algebra \mathfrak B , our method provides a Hopf algebra H such that \mathfrak B is a braided Hopf algebra in the category of H -comodules. It also serves as source to produce Hopf algebras generated by cosemisimple subcoalgebras, which are of interest for the generalized lifting method. We give several examples, among them quantum function algebras from Fomin–Kirillov algebras associated with the symmetric group on three letters.

Working and Resting Period based on Inclination, Loads, and Lift Methods on Manual Material Handling in Mining Environment

Working and Resting Period based on Inclination, Loads, and Lift Methods on Manual Material Handling in Mining Environment

Pumping wells super flexible closed-loop control technology research and testing applications

In the late period of oilfield development, beam pumping is the most common artificial lifting method. With many problems such as high energy consumption, low efficiency and poor working condition, conventional drive control and production management mode can hardly meet the need of development. In this paper, a method of super flexible closed-loop control for beam pumps is proposed. With coupling analysis of loads, power and position of crank in a pump cycle and calculating, motor speed and corresponding frequency output curve can be obtained. Thus, variable motor speed with very little change on power mode is achieved. Through the driving frequency output and the drive power change, the variation of loads, torque and power of the whole beam pumping system can be reduced. In this way, working condition and efficiency of the pump can be improved and the abrasion of rod string and energy consumption can be reduced, meanwhile, service life of the whole system can be prolonged. After field test, the result of energy saving and efficiency improving can be seen.

Experimental investigation on the performance of Electrical Submersible Pump (ESP) operating with unstable water/oil emulsions

Electrical Submersible Pump (ESP) is one of the most commonly used artificial lift methods in petroleum production, due to its capacity to operate in several conditions with two or three-phase flows. When the ESP operates with emulsion flow, its performance is degraded, and operational instabilities occur. Therefore, this paper aims to carefully investigate phase inversion and to present, by the first time, the effective viscosity of unstable mineral oil/water emulsions, within the ESP. The first part of this work analyzes the phase inversion phenomenon for two oil types in three viscosities, five ESP rotational speeds, and three mixture flow rates. Logistic functions were fitted using the dimensionless head as a water cut function to determine the phase inversion within the ESP. The continuous phase inversion model, developed for emulsion pipe flow, did not present a satisfactory agreement to flow conditions tested. An indirect method to determine the emulsion effective viscosity within the ESP was proposed, which was obtained from the water/oil emulsion performance curves. The viscous performance data were used to determine the parameters of a dimensionless head empirical model for the tested ESP. Thus, the calculated values were compared with the effective viscosity obtained with oil and water emulsions, as well as the ESP performance, operating with emulsion and oil, which provides similar values for low rotational speeds. The different behavior of the effective viscosity between the pipeline flow and within the ESP was observed for water-in-oil emulsions and may be related to the high centrifugal field in the ESP.

The usefulness and utilization of a detachable steel wire-rimmed retractor (KN retractor) for endoscopic thyroid and parathyroid surgery.

In endoscopic surgery, surgeons occasionally encounter difficulties due to visual field obstruction by muscles or blood vessels. In these situations, specialized instruments that can effectively retract these obstructions are required. Recently, we developed a new detachable wire-rimmed retractor (KN retractor) for narrow-space surgery. We evaluated the utility of this KN retractor in 15 patients with thyroid and parathyroid disease. Of those, five patients with papillary thyroid cancer had gasless endoscopic hemithyroidectomy with central node dissection, five underwent endoscopic total thyroidectomy for Graves' disease, and the remaining five received endoscopic parathyroidectomy with gas insufflation. Surgeons were able to perform meticulous operations in a satisfactory visual field supported by the KN retractor. In all patients, the strap muscles were preserved without cutting. The average operating time was 149, 154, and 81min in patients who underwent hemithyroidectomy with central node dissection, total thyroidectomy, and parathyroidectomy, respectively. Gas insufflation was successfully completed in all cases while maintaining sufficient airtightness. The KN retractor is suitable for both the gasless lifting method and gas insufflation surgery in a narrow space. We believe that the KN retractor is a new device that will greatly improve the safety and shorten the operation time in endoscopic surgery.

Comparison of the free vortex wake and actuator line methods to study the loads of a wind turbine in imposed surge motion

To enable the development of floating offshore wind farms, it is important to have a clear understanding of the aerodyamic forces applied on a floating offshore wind turbine. The paper presents comparisons between a lifting line free vortex wake method and an actuator line method in the case of a wind turbine in surge with blade-resolved CFD data as a reference. Each model is compared to a quasi-steady estimation of the loads to understand the variations due to the surge movement. The near-wake flow field is investigated in order to give an insight into the flow features leading to the observed behavior. Both methods predict a higher axial velocity at the position of the rotor and one radius downstream of the rotor in surge conditions compared to the fixed case.

Incision Edge “Lifting Method” in Cerebral Bypass Surgery: A Novel Optional Technique for Narrow or Thin Recipient Arteries

Cerebral bypass surgery, such as the superficial temporal artery-middle cerebral artery bypass, is one of the essential procedures for cerebral revascularization. However, very narrow or thin blood vessels will increase the risk of anastomotic problems, such as occurs in Moyamoya disease. For such vessels, we have devised a "lifting method" in the recipient arteriotomy. In the present study, we have introduced this novel optional technique and evaluated its effects. The lifting method is a procedure of lifting the incision edge of a linear incision on the recipient vessel to widen the ostium. We attempted the lifting method in 23 consecutive patients (41 arteries) and, as a historical control, compared the results with those from the conventional method in 25 consecutive patients (37 arteries) for the previous 3 years. We compared patient age, years of surgical experience, recipient vessel diameter, anastomotic events, and final patency. As a subanalysis, the same evaluations were performed separately for patients with Moyamoya disease. Furthermore, the time required for the lifting procedure was measured retrospectively. The incidence of anastomotic events with the conventional method was 13.5% overall and 19% in those with Moyamoya disease. No adverse events occurred with the lifting method (P < 0.05). No statistically significant differences were found for the other factors, including final patency between the 2 groups. The time required for the lifting procedure averaged 1 minute, 15 seconds. Use of the lifting method widens and secures the ostium in a recipient vessel and greatly facilitates operability. We have found it to be a foolproof method enabling safe and reliable anastomosis even with narrow or thin vessels.

Living With COVID-19: A Systemic and Multi-Criteria Approach to Enact Evidence-Based Health Policy.

The lifting of COVID-19 (coronavirus disease 2019) lockdown requires, in the short and medium terms, a holistic and evidence-based approach to population health management based on combining risk factors and bio-economic outcomes, including actors' behaviors. This dynamic and global approach to health control is necessary to deal with the new paradigm of living with an infectious disease, which disrupts our individual freedom and behaviors. The challenge for policymakers consists of defining methods of lockdown-lifting and follow-up (middle-term rules) that best meet the needs for resumption of economic activity, societal wellbeing, and containment of the outbreak. There is no simple and ready-to-use way to do this since it means considering several competing objectives at the same time and continuously adapting the strategy and rules, ideally at local scale. We propose a framework for creating a precision evidence-based health policy that simultaneously considers public health, economic, and societal dimensions while accounting for constraints and uncertainty. It is based on the four following principles: integrating multiple and heterogeneous information, accepting navigation with uncertainty, adjusting the strategy dynamically with feedback mechanisms, and managing clusters through a multi-scalar conception. The evidence-based policy intervention for COVID-19 obtained includes scientific background via epidemiological modeling and bio-economic modeling. A set of quantitative and qualitative indicators are used as feedback to precisely monitor the societal-economic-epidemiological dynamics, allowing tightening or loosening of measures before epidemic damage (re-)occurs. Altogether, this allows an evidence-based policy that steers the strategy with precision and avoids any political shock.

A combined method of oral commissure lifting for perioral rejuvenation in Asians

A drooping oral commissure shows an appearance of ageing and sadness. To improve it with less complications has become a rising aesthetic concern for Asians. To share our method for oral commissure lifting by a combined technique including skin resection, oral commissure suspension, and dissection of the depressor anguli oris muscle (DAO), and to present the follow-up outcomes. This was a retrospective study of patients who underwent oral commissure lifting between 10/2012 and 03/2019 at the Department of Plastic Surgery, Peking University Third Hospital. The patients were routinely followed at 1 week, 1 month, and over 6 months. After operation, cases with the cheilions (oral commissure points) located above the ipsilateral lateral thickening points were considered to be effective, with the points at the same level were considered to be mildly effective, and with the cheilions below the ipsilateral lateral thickening points were considered to be ineffective treatment. Surgery took around an hour. Swelling subsided within 9.2±3.4 days. The red color of the scar disappeared within 3.7±1.5 months and the natural facial expression was restored within 7.9±2.6 weeks. Among the 159 cases, 125 (78.6%) were obviously effective, 21 (13.2%) were mildly effective, and 13 (8.2%) were ineffective. After the first operation, 112 patients (70.4%) were satisfied, 39 patients (24.5%) were basically satisfied, and eight patients (5.0%) were unsatisfied. The combined technique for the oral commissure lifting displayed a significant effect with little complication in Asian patients.