Spring 2005 Gas-Lift Workshop Page 24
2005 Gas-Lift WorkshopTechnical Presentations
/Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:
Petrobras Deep Water Gas Lift Project (an Overview) / Company(ies):
Petrobras
Author(s):
Guilherme Peixoto
Paulo José Pinto Ribeiro
Alcino Resende de Almeida
Jose Eduardo Mendonça da Silva / Contact Information:
Abstract:
The Petrobras Deepwater Gas Lift Project is part of the PROCAP 3000 program and intends to face the challenges of gas lifting in high pressure and high flow rate deepwater wells. The main objective is to search for products that will optimize the gas lift process.
The work is focused in four areas of interest: study of scenarios, equipment development, software development, and gas lift automation. Phase 1 of the project is almost completed and Phase 2 will start soon.
The developed products, accomplished tests, and obtained results for Phase 1 of the project will be presented here, along with a summary.
Notes:
Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:The Bubble Breaker / Company(ies):
Shell International EP
Author(s):
Erik Schrama
Richard Fernandes / Contact Information:
Abstract:
The bubble breaker is an orifice plate that can be installed in a gas lifted or naturally producing well with associated gas to enhance production. By generating intense liquid turbulence the bubble breaker breaks up large bubbles and gas slugs into bubbles smaller than 1 mm. The small bubbles move slower through the liquid and are distributed more homogeneously over the cross section of the production tubing. As a result the small bubbles reduce the hydrostatic head in the well. To generate the turbulence and the small bubbles only a small pressure loss over the bubble breaker is required. If the well is deep enough and the gas-to-liquid ratio is within certain boundaries this results in a net reduction in flowing bottom hole pressure and an increase in production.
The bubble breaker project started as a co-called Game Changer project. At Shell EP Technology in Rijswijk, The Netherlands, different bubble breakers were tested in an 18-meter high, 72 mm diameter Perspex test facility. The proof-of-concept experiments showed that it is indeed possible to break up bubbles and that they can reduce the hydrostatic head significantly.
A field trial in Central Africa showed that the bubble breaker works. A production increase of some 10% could be seen and the flowing gradient survey showed a change in gradient.
Notes:
Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:Real Time Expert Systems For Production Optimization / Company(ies):
Petrobras
Author(s):
Edson Henrique Bolonhini
José Francisco Correa
Sthener R. V. Campos / Contact Information:Abstract:
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.
With this, the management of artificial lift methods has received an important partner from the control and automation engineering area. On the other hand, human resources training and the adaptation to actual installed instrumentation are some of the great challenges of this new field development tool.
Notes:
Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:Fiber Optic Temperature Systems / Company(ies):
Schlumberger
Author(s):
Vinicius Carvalho
Tommy White / Contact Information:
Abstract:
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.
Through the observation of Joule-Thompson cooling signatures, the DTS monitoring provided real-time visualization of the entire gas-lift system in real time and multiple valve activity, as well as tubing leaks, which allowed immediate problem identification and rectification.
An additional benefit from utilizing the slickline with fiber optics is the ability to monitor simultaneously the gas-lift system and the reservoir. Thermal analysis of DTS data revealed important inflow distribution information while measuring GLS functionality.
The DTS measurement has proven to be a superior tool for optimization of a Gas Lift system to the previously single point pressure measurement or gradient stops. Several case studies will be reviewed were optimization has been applied in real wells.
Notes:
Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:A High-Reliability Gas-Lift Orifice / Company(ies):
Shell International EP
Author(s):
Jim Hall / Contact Information:
Abstract:
As the industry moves to deepwater and subsea production, intervention costs increase significantly. Front end designs must consider artificial lift depletion plans to minimise life cycle costs. Higher lift gas supply pressures and more stringent regulatory agency requirements combine with the risks associated with floating structures to elevate the importance of wellbore integrity. Gas-Lift practices and hardware that have been acceptable for onshore and continental shelf operations become less financially appealing due to the high cost and risk of wellbore entries to service in-well gas lift hardware.
It is only recently that the industry has produced a step-change in the performance and reliability of the equipment planned for use in high intervention-cost wells. Designed operating pressures are increasing and well integrity issues are being addressed in hardware design. While onshore and shelf operations may accept the leak rates permitted in API Specification 11V1 (and soon ISO 17078.2), deepwater and subsea operations find as-built leaks unacceptable.
The High Reliability gas-lift Orifice (HrglO) was conceived to address a $1MM hard cost associated with a tubing leak tracked down to a $2000 leaking reverse flow valve in a gas lift orifice. A short brainstorming session produced several approaches which were then reviewed and ranked according to development time, cost and compatibility with existing hardware. A patent search produced a similar design to one of the concepts, but the maintenance payments on the patent had been stopped and so the intellectual property was in the public domain.
The concept of a flapper valve addressed the desire for a gas-lift orifice that removed the sealing surfaces of the check valve from the path of high velocity gas and liquids, the primary flaw in the design of traditionally used equipment.
The new design achieves the primary goals of isolating the check valve sealing surfaces, delivering a non-convoluted flow path and compatibility with existing equipment. Leak, flow and erosion testing has been conducted and field testing is planned for 1st half 2005.
Notes:
Session:
New Gas-Lift Technology
/ Session Chair:Jose Roberto Fagundes Netto, Petrobras
Presentation Title:Turbo Gas Lift-Innovative Hybrid Artificial Lift System / Company(ies):
INA, JSC, and TGL
Author(s):
Kresimir Kegleviae / Contact Information:
Abstract:
The operative costs of using ordinary continuous gas significantly rises as oil is lifted from greater depth. The reason is that higher and higher amounts must be compressed on bigger and bigger pressures, as depth rises. Furthermore, maximal intake gas pressure and maximal available amount of gas per well defined by surface gas lift equipment defines maximal possible lifting depth. Consequently, if fluid level into well falls below level of maximal possible lifting depth (defined by gas intake pressure and gas amount), then arises need for surface gas lift equipment redesign, or even introduce of other artificial lift type. The both situations commonly involves huge capital expenditure, which can be avoided by introducing turbo lift system on already using gas lift wells.
Furthermore, use of turbo lift causes huge energy savings compared with ordinary continuous gas lift, especially when static pressure decreases and situation of pressure surplus in gas lift system occurs.
Turbo gas lift method is based on combination of mechanical lifting by pump, and lifting by compressed gas (gas-lift). Pump in turbo lift system is powered by gas turbine fed by same compressed gas, which is after gives turbine power, is used for gas lift. By using compressed gas in such way, gas is doing two works instead of one, which leads to higher energetic efficiency compared with classic gas lift, especially in lifting from big depths.
The turbo gas lift system is combined with further main parts:
· gas turbine, fed by compressed gas from surface
· the pump for mechanic lifting of fluid up to above gaslift valve. Pump is powered by gas turbine.
· standard gas lift equipment which cotains working gas lift valve and release gas lift valves
Key benefits of turbo gas lift:
· increased volumetric efficiency-higher liquid volumes
· superior reservoir drawdown-increased production rate
· production stability-production of only desired fluid amount
· decreased gas injection requirements
· lower energy consumption
· prolonged continious gas lift
· decreased abandonment pressure
This presentation will show technology fundamentals, recent developments, and results of laboratory tests prior to field trial.
Notes:
Session:
Keynote Address
/ Session Chair:José Eduardo Mendonça
Presentation Title:No title submitted / Company(ies):
Petrobras
Author(s):
Carlos Tadeu Fraga / Contact Information:
Abstract:
No abstract submitted.
Notes:
Session:
Gas-Lift Software
/ Session Chair:Jim Hall, Shell International EP
Presentation Title:A Study of Flow Stability in Gas-Lift Wells Producing from Saturated Reservoirs / Company(ies):
University of Mexico
Author(s):
Y. V. Fairuzov, SPE
I. Guerrero-Sarabia / Contact Information:
Abstract:
Continuous flow gas-lift wells are susceptible to hydrodynamic instability (heading), which may cause cyclic variations of the wellhead pressure, and oil and gas flow rates. Gas-lift instability is a reason of many operational problems, for example, compressor shutdowns caused by pressure and liquid flow rate surges, difficulties in the operation of low pressure separators, and excessive gas consumption.
Stability problems in complex multiphase systems can be solved using stability maps. A stability map is a plane (2D) diagram that shows the regions of stable and unstable operation of the system, as well as its operating limits.
A study was performed to investigate flow stability in gas-lift wells producing from saturated reservoirs. Different stability criteria proposed in the literature were compared using a gas-lift stability map. Based on this study, recommendations on the selection of gas-lift stability criteria were developed. Several examples of gas-lift stability map applications are given. It was shown that stability maps enable designers and operators to determine rapidly the effect of gas-lift design parameters and operating conditions on the system stability. Gas-lift stability maps can also be used for training and educational purposes.
Notes:
Session:
Gas-Lift Software
/ Session Chair:Jim Hall, Shell International EP
Presentation Title:Lagrangian Transient Two-Phase Flow Simulator for Gas-Lift / Company(ies):
Petrobras
Author(s):
Kwon Il Choi
Ibere Nascentes Alves / Contact Information:
Abstract:
The Lagrangian transient two-phase flow model, based on a moving numerical grid, presents the important capability of tracking the gas and liquid’s kinematics precisely, and it’s not subject to numerical diffusion, which is the main drawback of the Eulerian models. At every time step, two moving grids, one for liquid and one for gas, are forzen and superimposed to make material and momentum balances possible. The finite difference cells become elastic, for their sizes vary all the time. The software developed from this new model has to deal with intensive search algorithms, interpolating methods and dynamic memory management.
Applying the Lagrangian model to simulate transient phenomena in Gas-Lift has proved very successful for studying unloading, instability, optimization and even effective gas-lift valve spacing. Other field operations that have been simulated include shut-in and start over. On the other hand, for showing its realistic and dynamic gas fraction distribution, the simulator has been used also as a good visual gas-lift training program. The presentation of this work includes some sample live simulations addressing main issues relating to Gas-Lift.
Notes:
Session:
Gas-Lift Software
/ Session Chair:Jim Hall, Shell International EP
Presentation Title:Dynamic Simulation / Company(ies):
ScandPower
Author(s):
Juan Carlos Mantecon / Contact Information:
Abstract:
Dynamic Simulation provides an improved process to optimize completion designs in complex wells (subsea, deep subsea, multilateral, multi-layer and smart wells). Dynamic Simulation is also essential to identify and understand the key flow assurance issues during the well’s life cycle. Improving the design and operation (field life cycle) of full production systems (from reservoir to process facilities) to obtain optimum production and minimize investment and operating cost is a very attractive exercise to maximize profit.
This presentation discusses the best current approach for implementing dynamic simulation and establishes its potential for evolving as the sole smart design/optimisation process for complex well completions and production systems to increase oil and gas production and optimise wells, pipelines, and facilities design. In the particular case of gas lift systems, Dynamic Simulation is also fundamental for optimising the well’s unloading process (transient). Dynamic simulation of production systems at early stage is essential to identify and understand the key flow assurance issues. It allows better project definition during the concept selection, FEED and detailed design phases. Dynamic simulation of operative production systems should minimize workover intervention and wireline activities, maximize safety, as well as enable operators to optimize, accelerate, and increase the recovery through the life of the well/field.
Additional benefits are obtained from real-time surveillance - faster detection and diagnosis of problems, and quicker response to failures.
Notes:
Session:
Gas-Lift Standards
/ Session Chair:John Martinez, Production Associates
Presentation Title:API Gas-Lift Recommended Practices / Company(ies):
Oilfield Automation Consulting
Production Associates
Author(s):
Cleon Dunham
John Martinez / Contact Information:
Abstract:
Gas-lift is major form of artificial lift. Many companies use it to produce large quantities of oil. It is being used more and more to assist in production of gas wells.
Starting in 1979, a group of people from the gas-lift industry came together under the auspices of the American Petroleum Institute (API) to develop specifications and recommended practices for gas-lift. To date, one specification and five recommended practices have been developed and two new ones are underway. These are:
Existing documents
– API Specification 11V1 – Gas lift valves, orifices, dummies– API Recommended Practice (RP) 11V2 – Gas lift valve testing, modeling
– API RP 11V5 – Gas lift operations (revision in progress)
– API RP 11V6 – Gas lift design
– API RP 11V7 – Gas lift valve reconditioning
– API RP 11V8 – Gas lift systems
Documents under development
– API RP 11V9 – Dual gas lift− API RP 11V10 – Intermittent gas lift
This presentation will highlight the purpose of each of these documents and how they can be obtained and used to facilitate training and best practices in oil and gas production companies.
Notes:
Session:
Gas-Lift Standards
/ Session Chair:John Martinez, Production Associates
Presentation Title:ISO Gas-Lift Standards / Company(ies):
Oilfield Automation Consulting
Author(s):
Cleon Dunham / Contact Information:
Abstract:
The International Organization for Standards (ISO) is producing gas-lift standards for the gas-lift industry. Currently, four standards are being developed:
· ISO 17078.1 – Side-pocket mandrels. Published by ISO in Dec. 2004.
· ISO 17078.2 – Flow control devices for side-pocket mandrels. First draft completed; starting international review process.
· ISO 17078.3 – Running, pulling, and kick-over tools, and latches for side-pocket mandrels. Being drafted.
· ISO 17078.4 – Practices for side-pocket mandrels and related equipment. Being drafted.
The existence of these standards will:
· Permit the user/purchaser to specify the equipment quality that is required for each specific application.
· Be assured that each piece of equipment is manufactured and tested according to specific requirements.
· Assure that new equipment suppliers who claim to meet these standards are required to demonstrate compliance with these standards.
This presentation will highlight the standards and the unique testing requirements that are associated with each device.
Notes:
Session:
Breakout Sessions
/ Session Chair:Cleon Dunham, Oilfield Automation Consulting
Breakout Session:Gas-Lift in Sub-Sea Wells / Company(ies):
Petrobras
Session Coordinator(s):
Jose Mendonca / Contact Information:
Notes:
Session:
Breakout Sessions
/ Session Chair:Cleon Dunham, Oilfield Automation Consulting
Breakout Session:Gas-Lift Automation / Company(ies):
Oilfield Automation Consulting
Session Coordinator(s):
Cleon Dunham / Contact Information:
Notes:
Session:
Breakout Sessions