ALRDC Technical Library

Document Categories


A Low Cost, Low Risk Method to Determine Lift Points Using Tracer Gas
by: Dees, Dan — Added 3/2/2009 12:00:00 AMGeneral - Gas-Lift Optimization

A low cost method exists to quickly and reliably determine lift gas entry point(s), such as open or leaking valves, without well intervention. The method creates a snapshot of well performance by introducing a small volume of CO2 into the injection line of a gas lifted well. A sensor placed at the wellhead, tree, or flow line separator monitors the amount of tracer gas returned in the production stream. From surface pressure and rate information, the depths of these measured returns are determined. This process is accomplished without production deferment or introduction of tools into the well bore. This information can be used to determine well operation after a work over, or assist in well integrity by locating entry points.

Applications of Downhole Sensor System for Gas Lift Well Performance Evaluation and Optimization
by: Oyewole, Peter O. — Added 3/29/2009 12:00:00 AMGeneral - Gas-Lift Optimization

Gas lift technology had been used extensively to dewater high reservoir pressure gas wells and tight sand formation with low permeability and productivity index (PI). However, its application in low reservoir pressure and depleted gas wells had been someway limited. Recent advancement in downhole sensor telemetry and packages, coupled with unconventional gas lift designs are enabling successful application of gas lift technology in low pressure formation.

This presentation is a case study on the application of downhole sensor for gas lift well optimization. The design covered in this presentation required high gas injection volumes at very low pressures. Adding downhole monitoring tools to the gas lift string assembly provided vital downhole pressure information. Real time downhole injection pressure, formation pressure, and downhole temperature were readily available.

Benefits of Detailed Compressor Modeling in Optimizing Production from Gas-Lifted Fields
by: Nadar, Manickam S. — Added 6/1/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Compression management plays an important, but often overlooked role in the optimization of gas lift networks. This paper describes the role of compressors in gas lift systems and explains why it is important to accurately account for compressor performance in full field networks.

Software tools are now available to assist the engineers in the modelling and simulation of complex fields with non-hierarchical production and injection networks. These tools are capable of solving the total system network and suggesting optimum values for critical parameters such as gas lift injection rates and pressures, and production system pressures.

Recent optimization studies of complex gas lifted fields have indicated that modelling of gas lift compressors as a part of the field network can uncover opportunities that add significant value in the operation of the field.

Case History of using Distributed Temperature Sensor (DTS) System on Slick line for Gas Lift Trouble shooting and Well Optimization
by: Sreekumar, M. P. — Added 3/2/2009 12:00:00 AMGeneral - Gas-Lift Optimization

DPC uses the Distributed Temperature Sensor (DTS) system on slick line to evaluate surging problem in a gas-lifted well and whether the gas-lift unloading sequence was functioning as designed. The technology was used in five wells with different objectives. This case history will provide insight into technology and the application used.

Key learning’s are:

1. Used to trouble shoot surging wells, where conventional Flowing Gradient Survey was not possible.
2. Identified out of sequence gas lift unloading in a well.
3. A memory pressure gauge was run in tandem with DTS fiber optic cable for capturing down-hole pressure reading that helped to verify and tune the well model.

Evolution Strategy Applied to Gas Lift Optimization in a Fully Dynamic Online Production Support System
by: Barroeta, Rafael; Beltran, Carlos Andres — Added 6/29/2009 12:00:00 AMGeneral - Gas-Lift Optimization

The optimization of gas-lift distribution in offshore oil fields imposes many challenges. Previous approaches to gas-lift optimization include the use of well performance curves, steady state flow models and techniques, and more recently, the use of evolutionary optimization algorithms combined with surrogate models.

The ever-changing nature of multiphase flow and the dynamic interaction of the different elements of a sub sea production system (including wells, manifolds, flow lines, risers, and separators) play a major role in determining how gas should be distributed in the different wells. The most rigorous approach to describe these dynamics is through the use of fully transient first principle simulation models. Whereas this is a well-established practice in the flow assurance community, there is no documented attempt on linking such models to sophisticated evolutionary optimization algorithms in an online environment.

This paper details a new online gas-lift optimization

Fiber Optic Distributed Temperature Monitoring for Gas-Lift Systems Optimization
by: Carvalho, Vinicius; White, Tommy — Added 4/14/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Distributed Temperature Sensing (DTS) technology has been successfully utilized in several artificial lifted wells to monitor and optimize their gas-lift systems. DTS data has been acquired using fiber optic slickline, which has proven to be a cost-effective solution to diagnose and optimize gas-lift systems, detect completion integrity issues and monitor reservoir inflow distribution.

Distributed Temperature Sensing (DTS) technology has been successfully utilized in several artificial lifted wells to monitor and optimize their gas-lift systems. DTS data has been acquired using fiber optic slickline, which has proven to be a cost-effective solution to diagnose and optimize gas-lift systems, detect completion integrity issues and monitor reservoir inflow distribution.

FieldWare Production Universe Closing the Loop on Optimization
by: Stroobant, Filip — Added 6/28/2009 12:00:00 AMGeneral - Gas-Lift Optimization

In conventional practice, individual well oil, gas and water production is only measured on a weekly or monthly basis using shared well test facilities. Oil and gas production from a cluster of wells is hence difficult to manage, leading to late diagnosis of production problems and slow and conservative handling of production constraints. FieldWare Production Universe (FW PU) is a software application developed by Shell that provides continuous real time estimates of well-by-well oil, water and gas production. FieldWare PU estimates are based on data driven models constructed and updated from production well tests and real time production data.

FieldWare PU data driven well models also facilitate continuous optimization by predicting changes to overall and individual well production as a result of changes to individual lift-gas rates, well production chokes or other set-points to maximize an objective function. Well set points are then computed for optimizing oil and gas product

Gas Lift Analysis & Production Optimization Using DTS
by: Staal, Timo; Brown, George — Added 3/2/2009 12:00:00 AMGeneral - Gas-Lift Optimization

This paper describes what distributed temperature profiling using optical time domain reflectometry is, what it's for, and why it adds value. The paper highlights the early data acquired from recent deployment activities on several wells. The vision is to be able to measure the 'health' of the well using it's (distributed) temperature as an indicator, rather than waiting for a problem to develop and having to diagnose it using 'post mortem' production logging activities. A permanently installed DTS fiber will eliminate the need for production logging to optimize or verify the(mal) functioning of gas-lift valves.

Gas Lift Optimization of Long Horizontal Wells
by: Mantecon, Juan Carlos — Added 3/2/2009 12:00:00 AMGeneral - Gas-Lift Optimization

The slugging flow conditions normally encountered in long horizontal wells are very difficult to predict using methods other than dynamic simulation techniques. Furthermore, when gas lift is being used to produce this type of wells, finding the cause of the slugging flow conditions becomes more challenging.

This presentation discusses terrain induced slugging flow and describes how the use of dynamic simulation techniques can predict this type of slugging and estimate slug size and frequency. Slugging cause by poor gas lift design is also discussed.

When the cause of slugging flow and the severity is known, changes in design and/or producing conditions can mitigate or eliminate slugging and optimize production.

Gas-Lift Diagnosis Using Welltracer Survey –Successful Trials in 20 Wells of Petroleum Development Oman
by: Peringod, Chandran; Clark, James; Barboussat, Didier; Peacock, Larry; Holloway; Jeff — Added 6/28/2009 12:00:00 AMGeneral - Gas-Lift Optimization

WellTracer, formerly known as CO2 WellTracer, is a method for troubleshooting gas-lift wells without the use of wireline tools. The WellTracer method is used to identify whether gas-lift valves on the production string are open or closed. It allows operators to quickly, easily, and accurately determine operating depth, whether any multipoint injection is occurring, and whether or not any gas-lift valves have failed. The WellTracer method may also be used to detect leaks in the production tubing above any fluid level that may exist. WellTracer surveys are accomplished by injecting a small quantity of CO2 (carbon dioxide) into the lift-gas stream at the wellhead and then by monitoring the CO2 concentration versus time in the produced fluid from the subject well being tested.

During the “L” field WellTracer Trial, a total of 20 wells were surveyed. All wells during the “L” field trial had between approximately 15 and 30 pounds of CO2 injected into them during the WellTracer survey. We

Gas-Lift Well Diagnostics in A Non-Ideal World
by: Kinderen, Wim der — Added 6/25/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Gas lift optimisation is easy when well and system models are calibrated and all relevant instruments and control devices are operational. It is a lot more cumbersome, but still possible, to diagnose problems and optimise the system if limited information is available. That is in particular relevant for subsea wells, where over-injecting lift gas reduces overall production. Repair of subsea instrumentation is expensive, so often an acceptable workaround has to be found. In many cases, information that is not readily available can be derived from other signals, using simple models or empirical relationships. For example, the annulus pressure correlates with injection flowrate, and - for subsea wells - the wellhead temperature drops when cold lift gas is mixed with hot well fluids. This is illustrated using actual data trends.

Integrated Field Modeling for Production Optimization
by: Nadar, Manickam S.; Olmstead, Clint Chester; — Added 6/24/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Operating an integrated production network can be a complex process. Production optimization involves operating at peak performance and resource allocation to the different fields. System upsets in one field can create problems in others. Changes to operating parameters, producing wells and the network distribution systems require re-iterations of the set points for entire system for optimization.

Dubai Petroleum Company is operating four fields offshore of the United Arab Emirates. The complexity of modeling and maintaining accurate models is challenging. Dubai Petroleum Company has implemented integrated field models for the production optimization and gas distribution systems. This presentation will outline the development process and timeline used to implement such a system, the results and benefits of the optimization and how it has impacted the business of the company. Finally, progress towards the next logical step - real time optimization.

Integrated Gas-Lift System Optimization Using Dynamic Simulation: A West African Subsea Field Case
by: Nass, Maria Alejandra — Added 6/24/2008 12:00:00 AMGeneral - Gas-Lift Optimization

In this study a dynamic multiphase flow simulator was used. Emphasis was placed on modeling the dynamics of the integrated production system. The study allowed establishing the deepest injection point based on the available compressor pressure for a range of gas lift rates. Another objective was to assure that instabilities in the flow regime (i.e. slugging) would be avoided by choosing the right depth for the operating valve in all of the wells; additionally, maximizing oil flow rate as excessive gas lift rates can hurt production.

Having the system as an integrated model (wellbores, annulus for gas lift injection and flowlines) allowed accounting for the possible interaction of each element and helped in determining an optimal setting depth envelope for the gas lift valves based on early, mid and late field life production data.

Kuparuk Gas-Lift Optimizer
by: Martin, Kenneth — Added 6/24/2008 12:00:00 AMGeneral - Gas-Lift Optimization

In 2005, ConocoPhillips Alaska installed a near-real-time optimization system at Central Processing Facility 3 in the Kuparuk River Unit.

This system, based on Petroleum Experts GAP software, is connected to the local automation system through proprietary software and Petroleum Expert's OpenServer product.

The new optimizer replaced an existing company-developed optimization program which used the "equal-slope" method of gas-lift optimization.

Central Processing Facility 3 is constrained on the amount of gas that can be processed, and within these constraints the optimizer was able to predict an increase of 200 BOPD over the existing system which did not account for back pressure.

This presentation will discuss the development, implementation, and initial results of the optimization system.

Optimising Production on Mature Gas-Lifted North Sea Assets – A Case Study
by: Ballantyne, Grant; Shere, Andrew; Handley-Schachler, Sybille — Added 6/24/2008 12:00:00 AMGeneral - Gas-Lift Optimization

This paper discusses the application of production optimisation to some of Talisman’s mature, gas-lifted North Sea assets. For the Claymore, Piper, and Clyde assets, the challenge was to increase production by optimising the usage of current wells and infrastructure with appropriate capital investment.

This paper illustrates how these challenges were met by building integrated detailed optimisation models using a commercially available software package. It shows how facility and production constraints were taken into account during the optimisation process to ensure that optimisation results were directly applicable to field conditions and how the asset model was able to predict and describe the complex interdependencies between wells, processing facilities, and gas-lift compressors and equipment.

Optimization of Well Clean-up Operation Using Gas Lift
by: Mantecon, Juan Carlos — Added 3/2/2009 12:00:00 AMGeneral - Gas-Lift Optimization

Well clean-up performance is evaluated, using dynamic simulation techniques, investigating the minimum stable rate and time required to clean up the wells in the MODU or FPSO when opening the well to production. Different initial drilling fluid conditions (brine-diesel) can be analyzed and the minimum gas lift rate required to unload the well can be established.

The knowledge of the minimum flow rates required to clean up the wells enabled appropriate design and sizing of well test equipment. Dynamic modelling can indicate if a standard well test package may be adequate for cleaning up a well completion or a high rate well-test package costing significantly more will be required. Dynamic modelling can indicate if gas lift is required to unload a well and/or a well-flowline-riser system full of fluids to a FPSO, and determine the minimum gas lift rate required.

Optimizing Gas Lift Equipment with CFD Techniques
by: Mendes, Rafael; Almeida, Alcino R. — Added 3/29/2009 12:00:00 AMGeneral - Gas-Lift Optimization

The present work explores the use of CFD (Computational Fluid Dynamics) techniques to improve performance of gas lift devices. Two cases involving high gas flow rate in gas lift applications were analyzed: pressure loss in the gas flow through the check valve of a venturi gas lift valve and the possible increase in oil production due to the simple change on the direction of the lift gas injection from downwards to upwards.

The results obtained with this numerical tool proved its value solving this class of problems and its potential for future applications. In the first studied case the check valve geometry was improved, resulting in a better overall gas lift valve performance. It was also shown that even when using optimized check valve geometry there is a limit in gas flow rate.

Real Time Expert Systems For Production Optimization
by: Bolonhini, Edson Henrique; Correa, José Francisco; Campos, Sthener R. V. — Added 4/14/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Expert systems focused on production optimization in Petrobras result from the combination of the petroleum engineer’s knowledge with automation techniques. In order to enhance intermittent and continuous gas lift efficiency and to adapt the system to the operational reality, different control methodologies have been developed.

This presentation will describe strategies based on pattern recognition and a close loop algorithm approach that are helping the production engineers to minimize oil losses, act remotely in distant wells, provide faster diagnostics, and gather historical trends to feedback petroleum knowledge at office desktop. Field cases from each technique will be presented, showing information from the supervisory and the data base architecture that is supporting these strategies.

Real Time Optimization of Gas Lifted Asset using Integrated Production Model
by: Dixit, Ashok — Added 6/28/2009 12:00:00 AMGeneral - Gas-Lift Optimization

Abstract Corrupted. Need to reload.

Unlocking the Value of Marginal Assets: “Production Optimization through Effective Integrated Production System Modelling”
by: Bikoro, Fortune — Added 5/22/2008 12:00:00 AMGeneral - Gas-Lift Optimization

Marginal fields are one of the word’s growing sources of oil, specially in mature oil producing regions where the production is declining, and the way to stem that decline appears to be in extracting new oil from smaller new fields.

Integrated production system modelling can be defined as the measure of operational health that provides an effective understanding of actual wells and field production performance.

Considerable savings can be made in terms of time using the integrated production system modelling concept to cycle through the entire production network, and predict the effects of changes through a systematic analysis of reservoir response, wells and flowlines behaviour and the impact of their interaction on field performance so crucial in marginal assets.

The presentation covers the approach taken to the problem of production optimisation in these marginal fields by using nodal analysis and network modelling as a cost-effective way to increase production.