AbstractThe oil and gas industry is continuously developing new technologies in answer to increasingly challenging demands. In the current market situation, where the oil price is dramatically reduced, these demands are strongly driven by finding the most cost efficient field development solutions. These solutions often call for stretching the requirements on subsea technologies. One solution that has been applied for years, with good track record, is the use of subsea boosting. Pressure on more efficient subsea boosting solutions has led to a number of development initiatives in the industry.Aker Solutions has, together with a few main oil companies, developed a new multiphase pump technology which is soon ready for the market. This will expand the operation envelope for subsea boosting and create better opportunities for more effective offshore field development. A parallel, and equally important, development activity has been the development of a new large duty, 6 MW, subsea motor.This paper will focus on the new 6 MW multiphase pump and motor developed and tested by Aker Solutions and its JIP partners. The step-wise applied development program will be reported, describing the main activities in the qualification of the new technology. Newly obtained results from the pump and motor qualification programs will be presented. Finally, an example will be presented on how this new boosting machine can be utilized to generate increased economic value for a subsea project.The new pump and motor opens up for improved field economics with a greater ability than ever before to maximize profit by increasing the oil recovery and reduce the total production time by, in some cases, several years. This has demonstrated to provide considerably improved net present value since the oil production peaks out years earlier.
The paper reviews the way leading up to the Subsea Factory Compressor Stations with focus on important technology step-stones and breakthroughs. A dedicated and long term focus on technology development through R&D has been carried out within a series of disciplines supporting the subsea production application. The development has been along two important axis; multiphase flow and subsea systems.
A comprehensive R&D effort was initiated in the beginning of the eighties resulting in a highly successful and profitable development and implementation on the Norwegian continental shelf, namely the subsea industry. Through a series of successful tie-backs and long distance multiphase flow lines, the ultimate concept was achieved for gas-condensate systems represented by the unprocessed transportation of well stream directly to shore. The first multiphase pumps were installed in the late -90 and in 2000 the first subsea separation station was started up. Today subsea boosting and separation is proven technology. In 2011, building the first subsea gas compression station was initiated, taken the last step to a full subsea factory installation.
To realise subsea compression, the main components have been subject to a systematic technology qualification process. The paper describes how Statoil's large scale laboratory facilities has been mandatory for full scale qualification testing as well as focus on quality to achieve the necessary level of confidence. The Subsea Compression projects solely, have carried out nearly 60 qualification activities, further detailed in the paper.
The paper also looks forward and point out that the subsea processing solutions that have been qualified and implemented can be utilized to achieve cost efficient solutions with low environmental footprint.
During a market condition that is characterized by volatile oil price, there is a strong incentive in the Oil & Gas Industry on maximizing the hydrocarbons recovery from existing fields, rather than initiating new field developments. For offshore deep water field applications, subsea boosting technologies are considered to be a solution to improve the field recovery, while also acting as enabling technology that allows for development of deep, harsh and stranded reserves, which otherwise deemed non-accessible. This paper presents the performances and application area of two novel subsea boosting solutions developed by Aker Solutions: 1. The boosting of condensate and oil as well as pressure increase by water injection through high pressure subsea pumps 2. The subsea boosting of gas flow with associated liquid, though high performance subsea compression.
The objective of this paper is to show how Well Access Technology is changing from field and project specific equipment packages to be subsea tree-vendor and field independent multipurpose systems developed during early 2000 for open water and landing string systems. Fifteen years of experience from performing Riserless Light Well Intervention (RLWI) on more than 350 different subsea wells has provided the knowledge to develop today's state of the art multifunctional subsea service technology. The experiences and synergies of RLWI operations have enabled continuous development of the technology to meet tomorrow's requirement in subsea services.
This Paper will give insight into the challenges experienced by going from standard methods with hydraulic power supplied from the surface through heavy and expensive, large diameter umbilicals, to stack integrated ecofriendly closed loop subsea electrohydraulic control system. Demonstration will be provided on how experience has enabled interfaces and communications both electrical and hydraulic, with various manufactures' subsea trees, through the use of modular and flexible solutions with services customized for desired operational needs for the short and long term throughout the life of field. Add-on control unit module enabling control of cross vendor systems will also be presented.
Technology, operational experience and standardization have evolved over the years and have resulted in a set of robust system building blocks, which enable multi-functionality. The most recent systems are able to perform a large number of operations on a multi-field basis. From early 2000's, combined Workover Control Systems (WOCS) have been developed. These enable operation between open water systems and landing string systems, as well as for control of multi-fields and multi-vendor systems.
The scope of RLWI service is currently being expanded. An optimization of the second generation RLWI system suitable for deepwater application in the USA GOM will be described featuring the latest generation of fiber optics, electrical and electro hydraulic technology.
The challenges in the installation of subsea structures are increasing very rapidly in the recent years. Larger and heavier subsea structures are being installed in harsh environments and in deep waters. Sophisticated lifting analysis is needed to establish safe installation criteria. Also, novel installation methods need to be devised to install heavy structures using small vessels.
In this paper, state-of-the-art installation analysis based on DnV-RP-H103 with a new approach to model the complex hydrodynamic loads at splash zone is described. Through recent installation work, this procedure is exemplified and the lessons learnt from the installation of subsea structures and long spools are discussed. A novel method by sub-surface tow, to install heavy subsea structure using a small construction vessel is out lined and the lessons learnt from installation of four structures are discussed.
The project experience showed that DNV-RP-H103 provides an excellent basis for the lifting analysis. In the recent North Sea installation campaign, by applying the new approach, a safe installation was performed at higher sea state. The sub-surface tow method proposed is robust and safe method to install heavy structures using small construction vessels and the lessons learnt from these installation campaigns clearly indicate that this method is easy, safe and robust in harsh environment.
Bufalini, Andrea (Centro Sviluppo Materiali) | Morana, Roberto (Centro Sviluppo Materiali) | Nice, Perry Ian (Statoil ASA) | Nasvik, Havard (Statoil Hydro) | Kjorholt, Halvor (Statoil ASA) | Bailey, Bill M. (Baker Oil Tools) | Adam, Mark Kendall (Baker Oil Tools) | Jiral, Dennis G. (Baker Oil Tools) | Ross, Robert Chapman (Baker Oil Tools) | Smith, Bob (Baker Oil Tools) | Ueda, Masakatsu (Sumitomo Metals Industries Ltd.) | Ohe, Taro (Sumitomo Metals Industries Ltd.)
While expandable tubular technology significantly increased traction within the oil&gas industry in the last few years, materials behavior knowledge for expandable casing has not progress sufficiently. This is due to the lack of a diffused definition of the most appropriate procedures to verify post-expansion material performance and to the difficulties in performing investigation activity. These investigations rely on post-expanded material, which is costly and time-consuming to obtain, especially for the range of very large plastic deformations applicable to Monobore applications.
Consequently, an extensive testing program was started by Statoil to define an appropriate testing procedure for the evaluation of material performance after expansion and to characterize candidate materials. This paper presents the testing methodologies developed and the results obtained for several carbon steel grades and CRAs. These evaluations included tests of the mechanical performance and the resistance to aggressive environments.
The assessment of mechanical performance was carried out through several conventional and innovative tests and evaluation activities. Conventional tests included tensile tests in longitudinal and transverse direction, at room and elevated temperature, impact tests and residual stress evaluation. Collapse tests were performed on expanded pipes. Novel methods with optical strain measurements were adopted for improved tensile tests. Finite Element Analysis of the expansion process was also used to further investigate post-expansion mechanical performance. The resistance to stress corrosion cracking or sulphide stress corrosion was evaluated by means of FPB and C-ring tests. Carbon grades were tested in a mild sour environment while CRAs were tested in aggressive environments representative of possible field conditions. All experimental tests were carried out on materials before and after expansion. The effect of strain aging was also evaluated for carbon steel grades applying a defined aging cycle to expanded material.
The experimental methods adopted are described and discussed. The test results highlighted the main mechanical parameters to be considered and allowed ranking the different materials tested. At least one carbon steel grade and one CRA possess adequate mechanical and environmental performance even after 30% expansion. The test methodology adopted was therefore considered adequate for the aimed purpose.
Tracers are applied as embedded in polymers that are placed in the downhole completion. The Tracer Systems are designed to change behaviour as a function of the surrounding medium. Such behavior can be the release of tracer into one medium while keeping tight in another. Released tracers will migrate to surface where topside fluid samples are analyzed and the tracer concentrations in those are the basis for extracting Well Inflow Information.
The Tyrihans well, B-IAH T2, was cleaned-up in two sections and the 1100m long toe section was equipped with 3 unique oil soluble tracers that were placed along the production zone. The objective was to evaluate the quality of clean-up and (if necessary) also during a production restart 6 months later. The well had a downhole temperature of 137oC, higher than the operating temperatures for available Permanent Tracer Systems. So a new Tracer System had to be developed and qualified for the case.
RESMAN's tracer systems indicate that the toe is contributing as expected to the fluid production and that additional production occurs along the well bore. All completion fluids in the lower completion seem to be fully cleaned-up. All 3 tracers adds value to the interpretation. Extra information on the fluid dynamics of the clean-up process could be indicated.
The Tyrihans Field
Tyrihans is an oil and gas-condensate field offshore Mid-Norway. Figure 1 show the two parts Tyrihans Nord and Tyrihans Sør. Oil reserves are 29 million Sm3 and gas reserves are 35 billion Sm3. The field is planned as a subsea project with 5 templates having a total of 9 producers and 3 injectors. Production from the Tyrihans field came on stream in July 2009. The field has been developed with a pure subsea solution, tied-in to the Kristin production platform via a 43km electrically-heated flowline. Gas for injection and gas-lift is received via another 40km pipeline from Åsgard B and water injection will be provided by large subsea pumps injecting raw sea-water. 4 of the planned 12 development wells have been drilled as of spring 2010 (3 oil producers and 1 gas injector). The oil producers are mostly long, horizontal, multi-lateral wells, with DIACS (Downhole Instrumentation And Control System) to monitor and control production. Production monitoring and allocation is enabled by comprehensive use of multiphase flow meters.
Subsea processing involves one or more combinations of fluid conditioning and pressure boosting of wellstream fluids and water at the seabed. The main benefits of applying subsea processing include increased hydrocarbon recovery and accelerated production, together with reduced CAPEX and OPEX, and HSE benefits.
This paper provides an overview of field operating experience for subsea boosting in the LuFeng field and the separation, produced water reinjection and fluid boosting applications at Troll Pilot and the Tordis fields, including the Tordis restart plans. The paper also describes design and installation of the Tyrihans raw seawater injection and summarises the gas compression technology qualification activities underway for the Gullfaks 2030, Åsgard Minimum Flow and Ormen Lange Pilot projects.
An overview of Statoil's future subsea processing opportunities is then presented and discussed, including new opportunities being assessed at the Norne and Astero and fields.
All aspects of subsea processing are reviewed, including boosting, raw seawater injection, separation, sand handling and produced water reinjection, and subsea gas compression technology. The important role of large scale testing and technology qualification, and close collaboration with key technology suppliers is described, together with a step-wise approach to deploying increasingly complex subsea processing systems in ever more challenging environments. Step out distance, water depth and harshness of the local environment for new fields are all increasing and new, more cost-effective technologies will be need to profitably develop future fields.
It is concluded that subsea processing has already provided positive business upsides, despite certain technical challenges, and Statoil expects to continue a stepwise development and deployment of subsea processing technology in the near and longer term future.
The paper provides an overview of and operating experiences with the subsea power supply systems for the Statoil fields utilizing high voltage power; Lufeng (seabed booster pumps), Troll (oil/water separation, water re-injection) and Tordis (separation, boosting, water re-injection). The paper gives a status on performance of the power system for these projects, and an overview of the most important "lessons learned??. The Tyrihans pump power supply system, which represents the world's longest step-out with topside VSDs and highest subsea motor power, is also briefly presented.
Future fields utilizing subsea processing at deeper waters and with longer tie-backs will require further development of power system technology and Statoil is undertaking several qualification programs for such applications. Status of Statoil's main ongoing qualification programs within HV power is given, including R&D and study activities. The overview includes status on all main power supply components such as motors, connectors, VSD, switchgear, transformers and cables/umbilicals within these projects.
The information provided gives a good overview of "state of the art?? of subsea HV power systems and components within Statoil, and can be useful to both manufacturers and end users of subsea power components.