Inflow Control Research Articles

On the Optimization of Conservation Law Models at a Junction with Inflow and Flow Distribution Controls

The paper proposes a general framework to analyze control problems for conservation law models on a network. Namely, we consider a general class of junction distribution controls and inflow control...

Outcome of liver resection for small bowel neuroendocrine tumour metastases

Background: Small bowel neuroendocrine tumours frequently metastasise to the liver. While liver resection improves survival and provides symptomatic relief, multifocal bilobar disease adds complexity to surgical management. Objectives: This study evaluated outcome in patients with small bowel neuroendocrine liver metastases who underwent liver resection at Groote Schuur Hospital and UCT Private Academic Hospital. Methods: All patients with small bowel neuroendocrine liver metastases treated with resection from 1990–2015 were identified from a prospective departmental database. Demographic data, operative management, morbidity and mortality using the Accordion classification were analysed. Survival was assessed using the Kaplan-Meier method. Results: Seventeen patients (9 women, 8 men, median age 55 years, range 31–76) underwent resection. Each patient had all identifiable liver metastases resected and/or ablated (median n = 3, range 1–20). Ten patients had major anatomical liver resections. Three patients had five segments resected, and seven had four resected. Nine patients (53%) had a concurrent bowel resection of the small bowel NET primary and a regional mesenteric lymphadenectomy. Median operating time was 255 min (range 150–720). Median blood-loss was 800 ml (range 200–10,000). Five patients required intraoperative blood transfusion. Hepatic vascular inflow control was used in ten patients (56.5 min median, range 20–150 min), which included hepatic inflow control n = 8, total hepatic exclusion n = 1, and selective hepatic exclusion n = 1. Median postoperative hospital stay was 9 days (range 2–28). Thirteen complications occurred in seven patients. Accordion grades were 1 n = 3, 2 n = 4, 3 n = 3, 4 n = 2, 6 n = 1. One patient required reoperation for bleeding and a bile leak. One patient died of a myocardial infarction 36 hours postoperatively. Sixteen patients (94%) had symptomatic improvement. Five-year overall survival was 91% (median follow-up 36 months, range 14–86 months). Conclusion: Our data show that liver resection can be safely performed for small bowel NET metastases with a good 5-year survival. However, a substantial number of patients require a major liver resection and these patients are best managed at a multidisciplinary referral centre.

Managing Recurrent Congestion of Subway Network in Peak Hours with Station Inflow Control

Station inflow control (SIC) is an important and effective method for reducing recurrent congestion during peak hours in the Beijing, Shanghai, and Guangzhou subway systems. This work proposes a practical and efficient method for establishing a static SIC scheme in normal weekdays for large-scale subway networks. First, a traffic assignment model without capacity constraint is utilized to determine passenger flow distributions on the network. An internal relationship between station inflows and section flows is then constructed. Second, capacity bottlenecks are identified by considering the transport capacity of each section. Then, a feedback-based bottleneck elimination strategy is established to search target control stations and determine their control time and control strength. To validate the effectiveness of the proposed approach, a decision support system coded in the C# programming language was developed, and the Beijing subway was used as a case study. The results indicate that the proposed method and tool are capable of practical applications, and the generated SIC plan has better performance over the existing SIC plan. This study provides a practical and useful method for operation agencies to construct SIC schemes in the subway system.

Применение устройств контроля притока в боковых горизонтальных стволах скважин пласта АВ4-5 Самотлорского месторождения

Применение устройств контроля притока в боковых горизонтальных стволах скважин пласта АВ4-5 Самотлорского месторождения

English

Production and injection in long reach horizontal wells pose several challenges in production optimization, flow assurance and reservoir management. Horizontal wells are known to be superior to vertical wells in terms of productivity, however, they are also susceptible to early water and/or gas cut production due to the heel-toe effect and/or permeability contrasts. Uniform distribution of water injection into all zones can also be a challenge in case of high-permeability streaks and fractures. To negate some of the adverse reservoir properties and to control the flow profile of production and injection fluids, downhole flow control devices are increasingly in use and beneficial in regulating flow, improved overall reservoir sweep, improved productivity from the tail section of the well and reduced water coning or gas cusping. Wellbore hydraulics for a long reach well completed with downhole valves have great influence on the reservoir performance and recovery in the long run. This paper presents a discussion aimed at better understanding of the critical challenges that long reach horizontal wells are prone to in terms of completion, as well as the developments so-far that have been applied to capture the physics across the long horizontal section. Three case studies are also discussed with some details emphasizing practical experiences of such wells.   Key words: Downhole flow controllers, horizontal wells, inflow control devices (ICD), internal control valves (ICV), production enhancement.

Design and Performance of a Novel Autonomous Inflow Control Device

Due to geological complexity and the heel–toe effect, the production profiles of long horizontal wells are usually imbalanced, and as a result, premature water breakthrough is usually encountered. Once water breakthrough occurs, this phenomenon will reduce oil production. To maximize oil recovery, inflow-control devices (ICDs) are widely used to create a uniform inflow profile. To date, known ICDs cannot meet all the ideal requirements throughout the well’s life. In this study, based on the combination of a successive restriction mechanism and water swelling rubber, a novel autonomous inflow control device is proposed. Then, the rules of oil–water two-phase flow through the novel design are studied by a numerical simulation based on optimized structural parameters, and the fluid property sensitivities are analyzed. Upon integration of the novel design into the test apparatus, flow tests are conducted. The influences of water content, inflow rate, and injection rate on the pressure drop are further analyze...

Extra-glissonian Approach for Total Laparoscopic Left Hepatectomy: A Prospective Cohort Study.

Laparoscopic liver resection under hemihepatic vascular inflow control has advantages over Pringle's maneuver, especially in patients with cirrhosis. From January 2016 to August 2016, 7 patients who underwent total laparoscopic left hepatectomy under hemihepatic vascular inflow occlusion using the extra-glissonian approach were included in this study. All were hepatitis B carriers and 4 had cirrhosis. The mean operation time was 247 minutes. The mean transection time was 110 minutes. No patient needed additional Pringle's maneuver. The mean intraoperative blood loss was 74 ml and no patient required blood transfusion. No open conversion happened. Postoperatively, no patient developed complications and there was no perioperative mortality. The mean resection margin was 2 cm. The mean hospital stay was 6 days. Upon a mean follow-up of 9 months, no patient developed tumor recurrence. The technique of total laparoscopic left hepatectomy using extra-glissonian approach was safe and feasible. The early surgical outcomes were good.

REBOA for the IVC? Resuscitative balloon occlusion of the inferior vena cava (REBOVC) to abate massive hemorrhage in retrohepatic vena cava injuries

The use of resuscitative endovascular balloon occlusion as a maneuver for occlusion of the aorta is well described. This technique has life-saving potential in other cases of traumatic hemorrhage. Retrohepatic inferior vena cava (IVC) injuries have a high rate of mortality, in part, due to the difficulty in achieving total vascular isolation. The purpose of this study was to investigate the ability of resuscitative balloon occlusion of the IVC to control suprahepatic IVC hemorrhage in a swine model of trauma. Thirteen swine were randomly assigned to control (seven animals) versus intervention (six animals). In both groups, an injury was created to the IVC. Hepatic inflow control was obtained via clamping of the hepatoduodenal ligament and infrahepatic IVC. In the intervention group, suprahepatic IVC control was obtained via a resuscitative balloon occlusion of the IVC placed through the femoral vein. In the control group, no suprahepatic IVC control was established. Vital signs, arterial blood gases, and lactate were monitored until death. Primary end points were blood loss and time to death. Lactate, pH, and vital signs were secondary end points. Groups were compared using the χ and the Student t test with significance at p < 0.05. Intervention group's time to death was significantly prolonged: 59.3 ± 1.6 versus 33.4 ± 12.0 minutes (p = 0.001); and total blood loss was significantly reduced: 333 ± 122 vs 1,701 ± 358 mL (p = 0.001). In the intervention group, five of the six swine (83.3%) were alive at 1 hour compared to zero of seven (0%) in the control group (p = 0.002). There was a trend toward worsening acidosis, hypothermia, elevated lactate, and hemodynamic instability in the control group. Resuscitative balloon occlusion of the IVC demonstrates superior hemorrhage control and prolonged time to death in a swine model of liver hemorrhage. This technique may be considered as an adjunct to total hepatic vascular isolation in severe liver hemorrhage and could provide additional time needed for definitive repair. Therapeutic study, level II.

Laparoscopic right posterior sectionectomy (LRPS): surgical techniques and clinical outcomes.

Right posterior sectionectomy is one of the most technically challenging laparoscopic liver resections. Currently, there is limited published data regarding the technique and results required to better understand its safety and feasibility. To report our experience, results and techniques, highlighting a variety of tips and tricks to facilitate this resection. A video is attached for technical demonstration. Retrospective review of prospectively maintained databases from June 2006 to June 2016. Three different techniques were used: resection following hilar inflow control, inflow control at Rouviere's sulcus and resection with intra parenchymal control. 29 LRPS were performed over a 10-year period. Median operative time was 240min (150-480). Pringle's manoeuvre was performed in 19 (65.5%) with a median total duration of 35 (20-75) min. Median perioperative blood loss was 600 (100-2500)ml. Additional liver resections were performed in 16 (55.1%). There were two(6.9%) laparoscopic to open conversions. Median postoperative hospital stay was 5 (2-30) days. The median size of the tumour resected was 25 (10-54) mm with median number of resected lesions were 2 (1-4), median free resection margin was 9.5 (1-45) mm, margins were infiltrated (R1) in two (6.7%) cases. There was one death within 30-days (3.4%). LRPS is feasible, efficient and safe. However, it is a technically challenging procedure and requires advance skills in liver and laparoscopic surgery. Surgeons should be familiar with a variety of approaches as each offers different advantages depending on the location and nature of the lesion, surgical preference and intraoperative findings.

Controllability and reachability of reactions with temperature and inflow control

Knowing the controllability properties of reactions may be critical in the design phase of controlled systems. Analysis of the controllability properties of reactions is done here with control inputs being the temperature of the reaction, and the inflow rates of some species. The analysis is based on the Lie-algebra generated by the vector fields related to the differential equation of the reaction. We prove that the chemical reactions are strongly reachable on a subspace that has the same dimension as the number of independent reaction steps in every point except where the concentration of reactant species is zero, and show that this result holds for reactions in continuously stirred tank reactors as well. Finally, we analyze the controllability of the anode and cathode reactions of a polymer electrolyte membrane fuel cell with the inflow rates of hydrogen and oxygen being the control inputs and show that by using the inflow rates as control inputs the dimension of the subspace on which the system is controllable can be greater than the number of independent reaction steps.

Ensemble clustering for efficient robust optimization of naturally fractured reservoirs

In the development of naturally fractured reservoirs (NFRs), the existence of natural fractures induces severe fingering and breakthrough. To manage the flooding process and improve the ultimate recovery, we propose a numerical workflow to generate optimal production schedules for smart wells, in which the inflow control valve (ICV) settings can be controlled individually. To properly consider the uncertainty introduced by randomly distributed natural fractures, the robust optimization would require a large ensemble size and it would be computationally demanding. In this work, a hierarchical clustering method is proposed to select representative models for the robust optimization in order to avoid redundant simulation runs and improve the efficiency of the robust optimization. By reducing the full ensemble of models into a small subset ensemble, the efficiency of the robust optimization algorithm is significantly improved. The robust optimization is performed using the StoSAG scheme to find the optimal well controls that maximize the net-present-value (NPV) of the NFR’s development. Due to the discrete property of a natural fracture field, traditional feature extraction methods such as model-parameter-based clustering may not be directly applicable. Therefore, two different kinds of clustering-based optimization methods, a state-based (e.g., s w profiles) clustering and a response-based (e.g., production rates) clustering, are proposed and compared. The computational results show that the robust clustering optimization could increase the computational efficiency significantly without sacrificing much expected NPV of the robust optimization. Moreover, the performance of different clustering algorithms varies widely in correspondence to different selections of clustering features. By properly extracting model features, the clustered subset could adequately represent the uncertainty of the full ensemble.

活性汚泥法における糸状微生物の発生と抑制に関する研究 : 第4報-実排水を対象とした間欠流入方式による抑制実験

活性汚泥法における糸状微生物の発生と抑制に関する研究 : 第4報-実排水を対象とした間欠流入方式による抑制実験

Resuscitative Endovascular Balloon Occlusion of the Aorta: Principles, Initial Clinical Experience, and Considerations for the Anesthesiologist.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is an endovascular technique that allows for temporary occlusion of the aorta in patients with severe, life-threatening, trauma-induced noncompressible hemorrhage arising below the diaphragm. REBOA utilizes a transfemoral balloon catheter inserted in a retrograde fashion into the aorta to provide inflow control and support blood pressure until definitive hemostasis can be achieved. Initial retrospective and registry clinical data in the trauma surgical literature demonstrate improvement in systolic blood pressure with balloon inflation and improved survival compared to open aortic cross-clamping via resuscitative thoracotomy. However, there are no significant reports of anesthetic implications and perioperative management in this challenging cohort. In this narrative, we review the principles, technique, and logistics of REBOA deployment, as well as initial clinical outcome data from our level-1 American College of Surgeons-verified trauma center. For anesthesiologists who may not yet be familiar with REBOA, we make several suggestions and recommendations for intraoperative management based on extrapolation from these initial surgical-based reports, opinions from a team with increasing experience, and translated experience from emergency aortic vascular surgical procedures. Further prospective data will be necessary to conclusively guide anesthetic management, especially as potential complications and implications for global organ function, including cerebral and renal, are recognized and described.

Technology Focus: Multilateral/Extended-Reach Wells (May 2017)

Technology Focus In a previous issue of JPT, I read an interesting comment. A petroleum engineering department had visitors. One of them was asked to draw a well on the chalkboard, and she instinctively drew a horizontal well. She obviously considered horizontal wells as common. This illustrates that, during the last decade, wells such as horizontal wells, long-reach wells, and multilateral wells came to be considered mature technologies. Another aspect is that the technical level has increased significantly during this development. Currently, in well engineering, there are also many activities designed to stretch limits, improve processes, and make solutions more competitive economically. The main objective of multilateral and extended-reach wells is improved field recovery. Multilateral wells expose more reservoir and improve reservoir drainage, whereas long-reach wells often increase drainage from existing platforms. Up to 80% of long horizontal wells may have inflow-control tools. The most common is the inflow-control-device orifice to control the water/oil contact, but more-advanced autonomous systems are being developed with more-precise control functions. A related group of tools includes water-stop mechanisms. Water production is a considerable challenge for the oil industry, from production, cost, and disposal perspectives. At present, there exist many useful completion technologies for inflow control and for workovers and stimulation purposes. New and improved functionalities open up for more-detailed reservoir analyses that ultimately will result in higher field recovery. The featured papers all show improved solutions for constructing multilateral and long-reach wells. They show the dynamics of a continuous striving for improvements. These well types are very important tools in the search to maximize recovery from petroleum fields. Recommended additional reading at OnePetro: www.onepetro.org. SPE 180445 Increasing Performance of Multilateral Wells Using Oil Fingerprinting by M.D. Jensen, ConocoPhillips, et al. SPE 183422 Korchagina P-108: Breaking ERD Records Offshore North Caspian Sea—A Case Study by Vasily Zvyagin, Lukoil, et al. SPE 184608 Reducing Well Costs and Extending Field Life With Intelligently Controlled Trilateral and Quadrilateral TAML Level-5 Multilaterals by Mark Glaser, Halliburton, et al.

A Methodology for Multilateral-Well Optimization

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 183004, “A Methodology for Multilateral-Well Optimization—Field Case Study,” by Ivan Cetkovic, SPE, Majed Shammari, SPE, and Talal Sager, Saudi Aramco, prepared for the 2016 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 7–10 November. The paper has not been peer reviewed. Multilateral wells with smart completions controlled by different flow-control technologies offer great operational flexibility, with each lateral able to be operated and optimized independently. Understanding the contribution of each lateral in the complexity of the system was a major objective of this study. In order to optimize the system and predict results under different operational conditions, a multilateral-well-modeling methodology was developed. This methodology covers two main factors affecting multilateral productivity—a flow-dependent gas/oil ratio (GOR) and interference between the laterals. Wells Overview The study was based on multilateral wells complete with inflow control valves (ICVs). As a general description, the wells are completed with three to seven laterals and each lateral is isolated by packers and controlled by an ICV, as shown in Fig. 1. Multilateral-Well Modeling A multiphase surface system flow simulator that is able to optimize production from wells and networks as an integrated system was adapted to generate and optimize the subsurface multilateral-well flow behavior. This simulator is used mainly for surface network modeling and optimization, but the complex subsurface well system was modeled with this application. This complex simulation model resolves and finds the optimal ICV pressure drop and diameter for each lateral for different inflow-performance conditions, such as different rate-dependent GOR curves at different operational conditions. The model was created as a black-oil model. In each lateral, the flow and pressure drop through the reservoir are determined in the horizontal section, as well as the annular flow between the casing and tubing. Each ICV is represented with a choke model. The primary method for validating a model is to match it to an observed production well test. This validation includes the requirement to represent flow and pressure at different operational conditions in order to predict operational conditions. A nodal analysis of a well model consists basically of two different curves—an inflow curve that represents the flow rate and flowing bottomhole pressure at different conditions and an outflow curve that represents the behavior of the pressure drop at different flow rates through the completion. The intersection of the inflow and outflow curves determines the operational point and is the point that needs to be matched at different operational conditions.

Performance of Horizontal Wells with Inflow Control Devices in Homogeneous Reservoirs with Bottom Water Drive

Horizontal well techniques play an important role in the development of unconventional oil and gas plays. A key challenge in horizontal well completions is that water cut will rise rapidly once water breakthrough without inflow control. Inflow control devices restrict flow by creating an additional drop in pressure to equal the drop in wellbore pressure in order to reduce water or gas coning. Once a control device is installed in the wellbore, it is almost impossible to adjust. As a result, it is extremely important to understand the oil–water pressure profile and the long-term behavior of well completions with ICDs. We use the theory of dynamic simulation-coupled well-reservoir flow to analyze the performance of horizontal well completions with and without ICDs using the multi-segment well model. This study proposes a new single-flow wellbore model and develops the model of oil–water flow in horizontal wellbore with influx. The performance of horizontal well completions with ICDs in reservoir with water drive is analyzed on the basis of the new coupled reservoir–wellbore model. Simulation results show that water breakthrough first occurs near the heel of the horizontal well due to the drop in pressure in the wellbore by the end of water-free production period in the homogeneous reservoirs. We also point out that completion with ICDs can optimize production in horizontal wells with long production sections, low drawdown pressure and high production rates. In these situations, the effects of a drop in oil–water two-phase pressure are significant.

Technical aspects and surgical complications of laparoscopic liver resection

Laparoscopic liver resection (Lap LR) is widely used to perform various types of LR and has replaced open surgery in many cases. As far as the technique is concerned, Lap LR is more difficult than open LR. The difficulty score (DS) was developed as a tool for evaluating the technical complexity of Lap LR and has been validated in several studies. In this review, we validated the DS in our case series and used it to compare our series with those described in a previous report. Improvements in blood flow control methods have also played an important role in the expansion of the indications for Lap LR. We reviewed the development of the inflow blood control methods used during LR. Biliary stricture is the most significant complication after Lap LR. Unfortunately, heat injuries are unavoidable when a radiofrequency (RF) surgical device is used to achieve hemostasis. We reviewed the methods used to dissect the liver parenchyma and treat biliary stricture in one of our cases. Although Lap LR is less invasive than open LR, clinicians should monitor patients for biliary stricture, as it is a severe complication that requires multidisciplinary planning and management.

Technical aspects and surgical complications of laparoscopic liver resection

Laparoscopic liver resection (Lap LR) is widely used to perform various types of LR and has replaced open surgery in many cases. As far as the technique is concerned, Lap LR is more difficult than open LR. The difficulty score (DS) was developed as a tool for evaluating the technical complexity of Lap LR and has been validated in several studies. In this review, we validated the DS in our case series and used it to compare our series with those described in a previous report. Improvements in blood flow control methods have also played an important role in the expansion of the indications for Lap LR. We reviewed the development of the inflow blood control methods used during LR. Biliary stricture is the most significant complication after Lap LR. Unfortunately, heat injuries are unavoidable when a radiofrequency (RF) surgical device is used to achieve hemostasis. We reviewed the methods used to dissect the liver parenchyma and treat biliary stricture in one of our cases. Although Lap LR is less invasive than open LR, clinicians should monitor patients for biliary stricture, as it is a severe complication that requires multidisciplinary planning and management.

The future of laparoscopic major liver resection

Laparoscopic liver resection has been gaining recognition in many parts of the world. The bloom is secondary to a successful consensus meeting in Morioka where surgeons around the world met and exchanged ideas. There is a strong need for laparoscopic major hepatectomy because the potential benefit is obvious if the risk and oncological outcome remain the same. It has been shown in many centers that laparoscopic liver resection can be done safely. Although there may be several variations in technique, the complex procedures of inflow control, bile duct division, parenchymal transection and hepatic vein division can be reproduced as in open hepatectomy. With appropriate coaching and increased case volumes, laparoscopic major liver resection will become a standard procedure in the near future.

Space mapping techniques for the optimal inflow control of transmission lines

In this paper we present an efficient optimization approach for the dynamic inflow control of electric transmission lines. For the description of transmission lines several mathematical models are available. Here, we focus on the telegraph network equations which consist of a coupled system of hyperbolic differential equations. The optimization is then to find the best possible energy input in terms of boundary control to satisfy given demands. To solve this problem we introduce space mapping techniques based on a first discretize – then optimize approach. The idea of space mapping is the consideration of two model hierarchies (fine and coarse scale), where the coarse scale model is less accurate but easy to solve. We explain how this method works in the framework of inflow control, design the corresponding optimization algorithm and present various computational results to show the numerical efficiency.