The undermentioned study looked at ways in which new engineering could be used to widen the life of the Albatross Field. Infill boring involves placing countries of bypassed oil and boring extra Wellss within the field to aim these countries.
The field requires elaborate seismal re-evaluation utilizing 3D & A ; 4D function to clearly place accretions of Attic oil and segmented countries. In the Forties field, Apache Oil has sustained a successful boring plan in all countries of the field during the past several old ages by using 3 D and 4 D seismal engineering to better place countries of the field that have non been adequately drained. 4D seismal mold has proved utile for gauging fluid motions at the Statfjord field, particularly for the midst, laterally uninterrupted sandstone reservoirs ( A. Hansen ) .
Once stray accretions are identified an infill boring plan can be prepared.
An analysis of current single good public presentation on the Albatross platforms should be carried out to indentify possible work-over campaigner Wellss. These Wellss can so be used to originate the in-fill boring plan understating the capital outgo required. The infill boring plan should if possible focal point on a batch stage on single platforms. This will understate the forces and equipment demands. After one platform has completed its planned agenda so forces and equipment can be transferred to the following platform. This will guarantee that a standardized system is in topographic point with experient forces who are familiar with the equipment and boring techniques being used.
Treatment of the injection H2O with the Brightwater system should be implemented to let extra by-passed oil to be swept from the reservoir. This would hike production rapidly whilst the infill boring plan was being implemented.
These Wellss should be planned and drilled to cross multiple compartmentalized subdivisions of the reservoir. Multi-lateral Wellss offer the best economic solution by greatly increasing the reservoir contact country available from the limited platform slots. These Wellss would be completed without cementing. Zonal isolation can be achieved with the usage of swellable elastomeric baggers and inactive influx control devices ( ICDs ) .
The Herring field development base instance should be changed from a individual production good in compartment C1 to a two leg many-sided production good and one injector well to let intersection of compartment C2. This would let entree to an extra 30 % of the estimated 40 million barrel STOIP. The production good would utilize the bing abandoned geographic expedition good to understate costs.
Table of contents
List of tabular arraies and figures
Large Oil and Gas ( BOG ) are the operators of the Albatross Field 150 stat mis offshore Aberdeen, Scotland in the Central Graben part of the North Sea. This is a mature field which is approaching the terminal of its commercial life. The Albatross complex consists of four platforms each of 20 slots named Albatross A, B and C and D located in 450 pess of H2O.
First oil was delivered in 1976. By 1985 the field was in peak production at 410,000 bopd and 14 million scf of gas. Entire STOIP was estimated at 4 billion barrels. At the terminal of field life, presently planned for 2010 an estimated 2 billion barrels will hold been recovered. The Brent group is divided into 4 units and the Statfjord group into 3. The sandstones are separated by shales which act as force per unit area barriers ( Figure 1 ) .
Figure: Albatross Field Stratigraphy
Two smaller undeveloped Fieldss, Halibut and Herring, prevarication within 25 stat mis of the Albatross composite. ( RGU, 2012 )
The undermentioned study assesses the options available for development of the outlying Halibut and Herring Fieldss and the renovation of the Albatross field. The study focuses on new engineerings available to increase current production degrees whilst cut downing operating outgo ( OPEX ) and recommends preferable constructs.
INCREASING Production OVER CURRENT Plan LEVELS
There are legion methods of increasing production over current degrees on Albatross. These include
De-pressuring of the Albatross reservoir.
Enhanced oil recovery ( EOR )
In-fill boring aiming untapped compartmentalised accretions and undrained Attic oil.
Development of orbiter Fieldss.
It has been shown nevertheless that that oil and gas production rates can be maintained and increased if the H2O injection is stopped and the reservoir is allowed to bring forth by depletion. ( Braithwaite, 1994 )
In 1992 the Brent field was de-pressured to increase gas and oil production. This scheme involved take downing the force per unit area within the field to below the bubble point, leting the solution gas to jailbreak and increase gas recovery from the production Wellss. ( Christiansen, et al. , 1997 ) .
The construct had 2 major drawbacks.
High initial CAPEX of ?1.3 billion to change over 3 of the 4 platforms to low force per unit area systems ( Jayasekera, et al. , 2002 )
Due to the lower reservoir pressures the infill Wellss had to be drilled through extremely depleted zones ( up to 4000 psi derived function ) . This caused important jobs with lost circulation nevertheless as ( names ) discussed in there ( Dtae anmd rubric ) paper this was non unsurmountable ( SPE 871740 )
ENHANCED OIL RECOVERY
Third recovery or enhanced oil recovery ( EOR ) techniques are being widely used with changing grades of success across the industry. The basic rule is that by utilizing chemicals, gas or steam and shooting them into the reservoir, residuary and bypassed oil will be swept from the well thereby increasing recovery rates.
Infill boring involves placing countries of bypassed oil and boring extra Wellss within the field to aim these countries.
Two options were looked at for the infill boring plan, Coiled Tubing Drilling ( CTD ) and Through Tubing Rotary Drilling ( TTRD ) . These are discussed in subdivision 4 of this study.
DEVELOPMENT OF SATELLITE FIELDS
Herring 1 is a Middle Jurasic sandstone reservoir around a salt nappy. It is classed as HPHT. The field is compartmentalised by 2 sealing mistakes ( Fig X ) . The compartments C1, C2 and C3 hold 60 % , 30 % and 10 % of the militias severally. One perpendicular geographic expedition well has been drilled in C1.
Figure: Herring 1 Structure
A base instance scenario developed by BOG calls for a individual horizontal manufacturer in C1 to
bring forth 8 million barrels over 7 old ages. Pressure care is required and a individual H2O injector is planned in the base instance.
A 2 leg many-sided well could be used to develop Herring 1. The production Wellss would be drilled organize the bing abandoned geographic expedition good to understate costs. The production watercourse would be routed to the Albatross A3 platform by a Framo multiphase pump. By using a pumping manifold it would let the 3 other Herring accretions to be developed by farther orbiter Wellss with minimum flowline demands and easier and more cost effectual tie-back.
The Framo MultiManifold provides a more compact trial and production system for subsea developments. Multiphase pumps can manage low recess force per unit areas, which make them ideal for take downing the streamlined backpressure of the well. With many Wellss, peculiarly those on unreal lift, significant additions and accelerated production can be achieved with even a modest bead in back force per unit area – sufficiency to in many instances justify the investing within a few months.
The downstream, Multiphase Pump Module boosts the combined flow from all Wellss back to the platform installation. The variable velocity pump can run at any gas/liquid volume fraction, up to 98 % . ( Coulthard, et al. , 2008 )
Multi-Manifold systems integrating multiphase boosting, multiphase metering and the multiport picker manifold make subsea multiplex systems highly compact with big weight nest eggs, and have important positive impacts on the field economic system either as a map of decreased CAPEX or OPEX or as a consequence of improved entire recovery ( J. Elde Framo Engineering, 2008 )
SUMMARY OF AVAILABLE TECHNOLOGIES
Multi sidelong Wellss cut down good building costs by increasing the usage of the expensive top hole subdivisions of Wellss. These offer the best economic solution by greatly increasing the reservoir contact country available but minimise the topside substructure and besides minimise slot demand on platforms.
These Wellss would be planned and drilled to cross multiple compartmentalized subdivisions of the reservoir. Figure 3 shows a basic schematic of a many-sided well.
Figure: Mutilateral Well Example
Intelligent completions are system that can roll up transmit and analyse good data. This information can be transmitted remotely intending no intercession is required to entree the information or to alter the well constellation. This reduces both capital outgo ( CAPEX ) and runing outgo ( OPEX )
Intelligent completion engineering ends are summarised as:
Prevention of everyday intercession for reservoir direction intents ;
Leveraged systems giving multiple skyline or reservoir incursions per good ;
Self-optimisation/automation of Wellss and procedure installations ;
Procedures will be designed as optimised systems instead than component footing ( eg, downhole/subsea V. Surface, installations and substructure ) ;
Intelligent completion system dependability will transcend 95 % operability 10 old ages from installing.
Early systems had a limited lifetime but as engineering and stuffs have improved so has dependability. Systems can be run with control lines to come up or in the instance of flow control devices can be inactive.
Halliburton has presenting a “ second-generation ” ICD, the EquiFlow independent valve. Initially, the valve maps as a conventional ICD. When H2O or gas discovery begins the tool senses which fluid is present and directs it up one of two tracts based on dynamic fluid belongingss. The oil way allows for comparatively unrestricted production, while the H2O or gas way greatly increases the force per unit area bead in the tool, thereby curtailing unwanted production. There are no traveling parts and no control lines and hence reduces OPEX associated with handling unwanted surface fluids.
Intelligent completions can be operated utilizing wireless engineering such as the Tendeka Floright system ( Figure 4 ) to command skiding arms and inactive ICDs. If this engineering is so farther expanded to wireless transmittal from the platform Engineers can supervise and set parametric quantities from an onshore location. Having Engineers based onshore reduces runing outgo by cut downing forces offshore and the associated conveyance and subsistence costs.
Figure: Tendeka Floright Completion System
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Swellable bagger engineering is one tool being utilised by operators to insulate multiple zones in openhole Wellss, and finally to cut down good building costs, extend good life, and better good unity.
Swellable elastomers are bagger systems which inflate to seal off either cased or unfastened hole ring and supply zonary isolation. Zonal isolation is required to forestall the cross-flow of fluids between geological beds and to cut down the volume of produced H2O. It is of import in these fortunes to accomplish the best possible seal between reservoirs. The elastomers are designed to swell in different mediums, oil based fluids, H2O, seawater etc. The baggers can be used in unfastened hole and extenuate the demand for expensive cementing operations.
Expandable tubulars are now being used to make monobore wellbores. The technique allows for a slimmer casing design with decreased tophole shell sizes whilst supplying a larger bottom hole subdivision therefore bettering production or injection rates. The system besides allows a grade of flexability should hole jobs be encountered where extra line drives can be run to instance off unstable formations or loss zones without compromising the overall good design. The usage of solid expandible line drives to make a monobore well has reduced good building costs by 30-50 % ( Weatherford RGU ) .
Casing boring involves casing off the wellbore as it is being drilled. This can be advantageous in countries where wellbore stableness or lost circulation is an issue. Troubles arise with the system when hard boring status are encountered and is non suited for really difficult formations ( BP ) .
ELECTRIC SUBMERSIBLE PUMPS ( ESP )
Electric submergible pumps are a signifier of unreal lift which use centrifugal forces to raise hydrocarbons to the surface, enabling high flow and enhanced production. The pumps can be installed in Wellss where production rates have fallen but installing can be dearly-won and intercession costs are high.
Assuming that production is worsening and that H2O cut is increasing one method being used to antagonize this is the BrightWaterA® system. Co-developed by Nalco, BP and Chevron, BrightWaterA® is a chemical that is assorted with the injection H2O and injected downhole. Tiorco a subordinate company of Nalco provinces in its proficient booklet that “ BrightWater atoms are a thermally active polymer that has been designed to trip based on the injection to production temperature gradient in the reservoir. Upon activation, the BrightWater nanoparticles begin to spread out up to 10 times their original volume. Once the atoms have expanded, they are retained in the reservoir and airt injection H2O into the untapped, oil-rich zones. This causes extra oil to be swept toward the bring forthing Wellss ” ( Nalco ) .
Figure: Brightwater Treatment Principle
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Artworks taken from SPE 84897
BENEFITS OF BRIGHTWATER
Enhances oil recovery in sandstone reservoirs.
Improves sweep efficiency in waterfloods.
Reduces permeableness of the stealer zone, directing injection H2O and oil to production Wellss.
Activates deep in the reservoir at a specific clip and temperature.
Disperses easy into injection H2O for downhole bringing.
Treatments can last for old ages.
No closure required.
Figure: Addition in Production after Brightwater Treatment
The boring plan should concentrate on aiming the crestal constructions of both the Brent and Statfjord reservoirs with horizontal many-sided Wellss.
CTD and TTRD have proven to salvage cost over conventional rotary rig operations peculiarly if the sidings can be performed through the bing production tubing salvaging clip and money from drawing completions and recompleting after boring. The other nest eggs occur when the kickoff takes topographic point within the mark reservoir therefore avoiding overlying cap stone shales. ( Scott, et al. , 1998 )
COIL TUBING DRILLING ( CTD )
High dogleg capableness, 45A°/100
Can non be rotated
Control of WOB can be hard
Small pipe buckles easy
Difficult to command downhole motors due to fluid compressibiliy
Potential overspeeding of motors
High hazard of differential sticking in low reservoirs
Poor hole cleansing and film editings conveyance
CTD ‘s high dogleg badness boring capableness of 45A°/100 pess or more consumes less TVD in acquiring to horizontal and gets to the mark quicker. On the other manus, CTD needs a comparatively stable formation to bore in. For illustration, it will fight through formations that contain reactive shales due to the inability to revolve and fringy overpull capableness.
THROUGH TUBING ROTARY DRILLING ( TTRD )
Can revolve the pipe.
Difficult to single-foot ( base ) the pipe in the derrick due to the built-in flexibleness.
The pipe is stronger than coiled tube.
Need to do connexions.
Damaged tube can be replaced easy in the drill twine.
Connections normally are disquieted externally increasing the diameter of the pipe.
Slower stumbling velocities when compared to gyrate tube.
Although a somewhat more expensive option than CTD, through tubing rotary boring ( TTRD ) carries less hazard of non productive clip ( NPT ) due to hole cleaning issues and spot trips. TTRD can besides accomplish longer horizontal subdivisions, +/- 1,000 foot longer than CT. ( Reynolds, et al. , 2003 ) The ability to revolve and the increased torsion and overpull capablenesss are better suited to long horizontal subdivisions in low reservoirs. TTRD is hence the preferable pick for an infill boring plan. The Wellss would be drilled utilizing a new clay system, WARPA® , designed by MISWACO. The system consists of micrometer sized atoms as burdening agents. The benefits include reduced ECDs and no exposure to barite droop. These will be advantageous when boring slimhole horizontal sidings.
The BHA will be an extremist slimhole design to let entree through the 5 ” completion tubing. The premise is that the ID is 4.369 ” API impetus. This will dwell of the Powerdrive X-bow, a motor driven geo-steering tool ( Figure 7 ) that can put to death unfastened or cased hole sidings. It has an built-in hole opener that gives it a scope from 3 1/8 ” to 4 A? ” . It has a 15A° dogleg badness ( DLS ) and has proven economical due to high ROP and steerability.
Figure: Powerdrive XBow Geosteering Tool
Slimhole MWD systems such as the ArcVision – multiple deepness probe, double frequence, array electric resistance compensated ( ARC ) and GR are now available and to the full field proven. These tools allow accurate geostreering guaranting maximal reservoir exposure with minimal hole drilled. The truth of Thursdaies systems limits the hazard of dry hole or of wrong good arrangement.
The BHA will be run on 2 7/8 ” 8.7 lb/ft P-110 tube with Hydrill 533 connexions ( Figure 8 ) . This pipe provides the best mechanical belongingss for torsion, tensile strength and buckling.
Figure: P-110 Tubing Specifications
Slim-hole ( 3.5-inch ) MPas baggers have been successfully run and set with slender inflow control devices ( ICDs ) through an expandible line drive. This engineering has been used successfully in sandstone reservoirs by Saudi Aramco ( Al-Mumen, et al. ) and by a major North Sea operator looking to utilize through tubing rotary boring to depart a mature good in the UK Continental Shelf. The well was completed on clip and within budget, presenting nest eggs of more than US $ 10 million over a conventional siding ( Tendeka )
By using a many-sided well in the Herring field an extra 30 % of the 40 million barrels of militias will be accessed. The initial individual production good was expected to bring forth 8 million barrels over 7 old ages. The extra many-sided leg should let this to increase to 12 million barrels over the period presuming that both compartments have indistinguishable reservoir belongingss.
Slimhole sidings from the bing platform Wellss is the best solution to entree by-passed oil in the Albatross field. The slimhole engineering along with swellable bagger completions is the most cost effectual solution to increase production.
SUMMARY OF IMPLEMENTAION ISSUES
Boring slimhole Wellss has several execution issues. Slimhole boring equipment is non every bit abundant as conventional sized equipment and in some instances will hold to be manufactured to order. This could do lead clip issues and extra back-up equipment will hold to be sourced and available at the start of the boring run. An incorporate attack should be looked at whereby one service company would supply all the necessary constituents for the well. McIninch et Al in there SPE paper described a new coaction between service company and oil company where there was a risk/gain portion agreement put in topographic point. The decision from this was that such understandings could be good to bith parties. ( McIninch, et al. , 2002 )
Other considerations are that rig crews are non routinely working with little diameter tubulars and preparation will hold to be implemented in both cannular handling and associated boring and good command patterns.
Treatment of the Albatross field with the BrightwaterA® system is a simple solution to increase oil production from bypassed accretions. The intervention does non affect any intercession work and procedures and production are non interrupted.
Seismic re-evaluation of the field should be carried out to place bypassed oil militias and a elaborate survey of platform good productiveness undertaken. From these consequences the worst executing Wellss can be used for an infill boring plan utilising TTRD and slimhole completion designs.
The Herring 1 chance should be developed with a 2 leg many-sided drilled from the bing abandoned geographic expedition good.
Figure: Hazard Matrix
High intercession costs in the instance of failure
Poor hole cleansing and high hazard of stuck pipe
The undermentioned Persons and Companies are acknowledged for their helpful advice:
Barry Fraser ( Wells Team Leader ) Eon Ruhr Gas.
John Sweeney, Subsea Supervisor
Peter John Gaskell BP Caspian Ltd ( once Schlumberger and Flopetrol )
The Robert Gordon University, ENM212 Advanced Well Engineering, Coursework.
SPE 77671, “ A Case Study: Using Modern Reservoir Characterization to Optimize Future Development of a Mature Asset ”
A. Hansen, A. Brendsdal, D. Schistad Arnesen, and M. Morris, “ Optimization of an Aggressive Drilling Program at the Statfjord Field-Maximizing Production in a Mature Field, ” by Statoil ASA, originally presented at the 2002 SPE European Petroleum Conference, Aberdeen, 29-31 October. SPE 78347.
Oil And Gas Production Handbook, An debut to Oil & A ; Gas Production, Havard Devold, 2006 ABB ATPA Oil & A ; Gas
Peter John Gaskell “ Permanent Monitoring – Looking at Lifetime Reservoir Dynamics.