bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a High-Fatigue-Life Mechanical Spoolable Connector
Authors: Ehtesham Asif , Hriscu Joseph , Zhong Allan
Published: April 2008

Due to limited crane capability, some coiled tubing (CT) strings are transported in two or three sections to offshore locations, requiring the use of welding or mechanical connectors for reassembly. CT utilization subsequently can be hampered by welding issues as well as lack of integrity of the connectors. Field welding techniques and commercially available spoolable connectors can decrease the fatigue life of CT string to 35–70% of the base tube.

This paper describes the development of a mechanical spoolable connector with a fatigue life as good as that of the base pipe. The connector was designed using extensive nonlinear finite element analysis (FEA) design iterations. The connector pressure rating is equal to that of the pipe, and the connector maintains its sealing ability throughout the fatigue life of the pipe—even on very aggressive radius drums and tubing guides. The connector conforms very well when spooled to the drum without "sticking out." The connector assembly OD fits flush with the CT string, providing continuous gripper engagement. Single or multiple connectors can be used to join sections of coiled tubing in the yard or on location.

The new connector uses material certified for sour wells and acid jobs, and its seals are compatible with a variety of chemicals, acids, and sour service conditions.

In addition, the testing of the connector is discussed. The connector design performed very well according to several prototype tests on a fatigue machine and full-scale yard test. The results demonstrate that the new spoolable connector can increase the utilization of CT with various configurations and enable operations previously not deemed feasible due to various limitations imposed by other joining techniques.
Milling of Cast-Iron Bridge Plug With Electric-Line-Conveyed Technology
Authors: Rattray Frank , Annandale Alex , Oil Marathon , Grassick Rob
Published: April 2008

A new application of well tractor robotics in combination with well milling technology has been proven in the UKCS. In June 2007 on a North Sea platform, well tractor robotics in conjunction with a well milling rotational unit, using an electric wire line cable, were used to remove a cast iron bridge plug at 16,000-ft.

A cast iron bridge plug run for a water shut off was set at an incorrect depth. Through evaluation, milling tests onshore confirmed that the concept of using a well miller with a well tractor was viable. The total operational time from rig up to rig down was 67 hours, with an actual milling time of 16 hours. During this unique operation all milled material was recovered and the challenges of controlling rate and milling penetration were achieved.

This new application for milling well completions hardware and other well bore obstructions offers a cost efficient alternative technology to existing methods. The proven technology, normally used for production logging in highly deviated wells, also offers HSE benefits and logistical advantages.

The article will describe the actual process from testing to completion of the offshore operation.
HP/HT Compact Motorhead for Larger-OD Coiled-Tubing/Jointed Pipe Operations: Design, Testing, and Successful Case History
Authors: Ehtesham Asif , Hriscu Joseph , Howard Robert
Published: April 2008

With the increased use of larger-sized coiled tubing (CT), demand for CT tools is pushing the limits of tool rating and frequently extending the sizes required for jointed tubing operations. This paper describes a high-pressure, high-temperature (HPHT) motorhead designed for larger-sized CT and/or jointed pipe. Motorheads are used for well control, emergency-release disconnects, enabling circulation to the annulus, and establishing circulation to the annulus should the normal circulation path become plugged.

The development and design of the new motorhead will be described, including its special mechanical capabilities that depended on careful alloy and elastomer selection. For example, the flapper valves can withstand 20,000-psi differential pressures in -40 to 400°F temperature cycles (from cold–hot–cold) in a single run. The flappers were designed to close in slam-shut situations without compromising well control, and the hydraulic disconnect can bear higher torque and tensile loads than any similar tool currently available.

The completion fluid in combination with the well fluids presented problems for conventional sealing compounds exposed to pressure and temperature extremes. Results from a two-month testing period are discussed, which included pressure, temperature, tensile strength, torque, and fluid compatibility tests. FEA and CFD analyses were used to simulate flow, pressure, and slam shut conditions, enabling the most effective motorhead design for HPHT environments.

A North Sea case history of a successful well intervention using the new motorhead is also described. Three fully certified traceable HPHT motorhead assemblies were used for six runs over a combined 121 days in wellhead pressures up to 10,800 psi and downhole temperature of 365°F. The tool was tested and serviced between runs. Under these rigorous conditions, it was critical that the valves held backpressure and retained their integrity after continuous pumping under high pressures and temperatures—these objectives were achieved.
Application of a Novel Rigid-Setting Material as an Annular Barrier to Re-establish Pressure Integrity of Tubing in an Injection Well
Authors: Setiadi H. , Bewick D. , Blair J. , Walger R. , Ridley E.
Published: April 2008

In a BP well on the south coast of England, pressure and fluid from the injection tubing were in communication with the annulus because of a leak path formed by corrosion of the tubing. This communication limited the maximum allowable injection pressure, which impaired the flexibility of the operator to manage the recovery program and thus reduced the recovery of hydrocarbons from the reservoir. Remedial treatment possibilities had to be compliant with considerations for the future abandonment plans for the field in that any treatment should not substantially impede or detract from efficient abandonment operations. A recompletion was not considered cost effective, and a mechanical straddle of the correct length was not viable. An annular barrier was chosen as the cost effective option when considering well life. Previously, the material predominately used to form the annular plug in similar situations was oilfield cement placed onto the production packer in the annulus. The alternative, novel rigid setting material, was chosen because of its differing suitable properties, which are (1) a high level of resistance to contamination, (2) expansion, (3) ease of milling, and (4) 100% acid solubility. These properties helped ensure that a uniform plug was achieved though the material was diluted by annular fluid between the production packer and the punched circulation holes in the tubing, and that a good seal was created so that the annular plug was not bypassed. Further, excess material can be easily removed from the tubing to bring the well on line with minimal delay and future abandonment operations are not onerous. In late 2006, the slurry was placed using a coiled tubing (CT) packer arrangement, with displaced fluid returned to surface for environmentally safe disposal. The ease of placement and reliable set of the material, with strength comparable to normal oilfield cement, can provide an effective alternative to commonly used annular sealing materials.
Pressure Transient Analysis Data Collected by the Use of a Retrievable Gauge Hanger in Saudi Arabian Gas Wells
Authors: Zbitowsky R. , Nunez Garcia W. , Al-Shawaf A. M. , Al-Hussain H. M. , Bill B.
Published: April 2008

Up until today operators have been facing a challenge on how to place memory gauges as close to the perforations as possible when collecting data to perform pressure transient analysis. Various methods have been used including hanging the memory gauges in nipple profiles or below a retrievable packer or even setting the memory gauges at the bottom of the well to be retrieved later. Suspending the memory gauges in the well using slick line is another commonly used method in certain areas.

Pressure transient analysis (PTA) plays a key role in determining reservoir parameters for both stimulated and non stimulated wells. Some of the results from PTA include permeability, skin factor, flow efficiency, average reservoir pressure, system geometry and reserve estimates.

To make the collection of such key data more efficient in both vertical and horizontal wells Saudi Aramco is now using a Retrievable High Expanding Gauge Hanger®, Figure 1, which has been designed incorporating a large by-pass flow area to minimize restriction in the wellbore. With a simple adjustment the hanger can be set in 4½ in., 5 ½ in. or 7 in. tubing or casing. The tool can be run through smaller ID tubing and set in larger ID liners and is designed for the memory gauges to hang below. The tool is run on slick line and set using a non-explosive hydrostatic setting tool. Retrieving the tool is easy utilizing a standard JDC Pulling Tool. High levels of H2S and CO2 in some Saudi Arabian gas wells required the re-useable hanger to be made from an Inconel® material.

This paper will compare the different methods used for data collection; discuss the development process of the gauge hanger tool as well as the final design of the hanger and setting tool currently being used. Case histories will also be presented from several prolific Saudi Arabian gas wells.
Development of Wells Technical Professionals
Authors: Smith Angela , Skar Olav , Morse Tony
Published: April 2008

The Wells function in Shell International Exploration and Production has long been recognised as leaders in competency development. As part of the ongoing Shell Global Business Performance Reviews it was deemed important to improve and expand the role of Wells learning in the organisation and link it more closely to competency development. Part of this requirement was to ensure the new learning was of an internationally recognised and accepted standard.

Shell Wells Professionals now have the opportunity to gain academic degrees of Master of Science, MSc, as part of their learning and development (L&D) programme. A new dynamic approach within the Shell Learning Centre has been able to integrate both new and redeveloped Shell training courses with a Scottish University validation.

The redeveloped "Drilling Round 2" course, a Shell standard for some 35 years, now includes the increasingly important area of Completions and Well Interventions. New learning materials, delivery methods and training philosophies have been brought together in a seamless programme that delivers world class development for Wells Engineers. This reflects steps Shell has taken in support of a life-of-field philosophy in the planning, construction, operation and maintenance of its well assets.

A new breed of highly trained, competent and motivated professional engineers is emerging with a much greater understanding of the need for interdisciplinary communication and knowledge transfer globally. Not only does this result in an enhanced career path for individuals but also benefits Shell directly in that the investment in Learning and Development improves Shell's Wells performance in terms of safety, environmental management, integrity and efficiency.
Comparison of Computational Fluid Dynamics of Erosion in Coiled Tubing to Field and Test Data
Authors: Rosine R. S. , Blanco I. L. , Bailey M.
Published: April 2008

Coiled tubing (CT) is used as a cost-effective means of servicing wells for well intervention. Over the years, the fluid flow through CT has been discussed and theorized. Testing has been conducted to promote a better understanding of what happens inside the CT. In recent years, the use of computational fluid dynamics (CFD) software has provided greater insight into actual CT flow patterns, including fluid-flow velocity profiles, secondary flow regimes, and erosion. CFD helps to understand the CT fluid flow phenomenon, which can lead to effective tubing management. CFD has proven to be an effective alternative to full-scale testing.

This work compares the results of CFD modeling of erosion to actual field data. It compares predicted values, actual values, and computed values from the CFD solutions. CFD is used to provide correlations for the predictive model without full-scale testing, which greatly reduces the cost of development. Fluids investigated include slurry pumped from an actual job and full-scale testing.
The Effects of Residual Bending Forces on Coiled-Tubing Injector
Authors: Rosine R. S. , Bailey M. , Blanco I. L.
Published: April 2008

Coiled tubing (CT) injectors have been used in well intervention (WI) service for many years. As the WI business becomes more challenging, it requires the use of larger tubing. Using larger tubing results in managing tubing strings and operating equipment in a different manner. Tubing strings have become larger in size and yield strengths of the material have increased. Larger and stronger tubing subjects the equipment to greater stresses. The tubing also has more residual bending forces than the smaller, more traditional strings used in the past. The increased residual forces can affect the performance on the injector, adversely affecting the gripper beam pressure in particular.

This paper discusses the results of residual bending forces and their effects on the CT injector. It compares computed values to actual values from experimental test data. The findings could change the effective gripper beam pressure.
Pushing the Wireline Operation to New Frontiers
Authors: Al-Dhufairi Mubarak , Al-Ghamdi Abdulrahman , Lewis David , Nafa Hamed
Published: April 2008

This paper presents a case study of field trials completed by Saudi Aramco to evaluate use of the Wireline Engineering Company's Roller Bogie™ tool to improve wireline (both Slick and Electric Line) intervention in highly deviated cased-hole wells. Conventional wireline intervention tool operations are normally limited to a maximum of 65° inclination due to frictional resistance between the wireline toolstring components and well tubulars. The Roller Bogie™ tool was used to overcome well inclination limitations and complete necessary wireline interventions without the utilization of costly and complex coiled tubing or wireline tractor operations.

Conceptually, the Roller Bogie™ tool drastically reduces frictional contact between the wireline toolstring and the wellbore tubulars by lifting the entire wireline assembly off the well tubulars on low-friction rollers. Moreover, the Roller Bogies™ uses a self-orienting body profile to ensure that the rollers are always located on the low side of the tubing and also have integral swivels that allow the rollers to be oriented independently to the rest of the toolstring.

The use of this tool in Saudi Aramco wells has enabled conventional wireline operations to be conducted at well deviations in excess of 82°. The Roller Bogie™ tool was used in tandem with a cement bond log (CBL) tool in an offshore highly deviated (maximum of 87°) cased hole oil well at a depth of 9,154 ft (2,790 m). This CBL log was recorded successfully at a maximum of 82° of inclination and to a depth of 8,406 ft (2,526 m) without any significant wear out or damage to the Roller Bogie™ tool or attached wireline assemblies.

After the success of the trial test operation and the resultant cost avoidance of the coil tubing or wireline tractor utilization, additional operations were completed, such as bridge plug installation, perforating and ceramic disc rupturing.
CT-Failure Monitoring: A Decade of Experience
Authors: Crabtree A. R.
Published: April 2008

In its earliest days Coiled Tubing (CT) suffered from unreliability due to low cycle fatigue and inconsistent material performance. With the introduction of the continuous milling process utilizing the bias weld geometry to join lengths of flat strip before forming the tube and an improved material specification, the industry was able to measure fatigue performance accurately and develop predictive algorithms to avoid over use of the tubing.

Since those early days the reliability of CT has improved and allowed the industry to expand rapidly to the point where there are now approximately 1,500 CT units in operation around the world. This growth has also expanded the range of pipe sizes, wall thicknesses, string lengths, steel grades and types of operations being utilized or undertaken. The operating environment in which CT is routinely used has become more arduous with interventions being performed in high pressure wells, sour gas wells and geothermal wells, for example. The expansion of the industry, especially over the last 5 years, has also led to a dilution of knowledge and experience as companies compete to hire and retain staff.

The expectation might be that all these factors combine to reduce the reliability of the coiled tubing service at the well site. This paper will review a decade of tracking CT failures, their cause and will set the results against the perspective of the changing nature of the business over the same time period. Conclusions will be drawn as to what are the critical factors for obtaining reliable CT service life performance and whether or not reliability is higher today than a decade ago.
Improved Method for Underbalanced Perforating With Coiled Tubing in the South China Sea
Authors: Rae Graeme , Yusof Mohd. Bakri , Ghani Juanih , Mokhtar Shahril , Munro Jock
Published: April 2008

In Malaysia, coiled tubing (CT) conveyance is used to optimize underbalanced perforating, especially for rig-related operations. Well trajectory, temperatures and fluids can create uncertainties on both depth control, and the accuracy of hydrostatic cushion before firing the guns. The conventional method of correlating the CT on depth involves two CT runs the first to run a memory gamma ray (GR) and casing collar locator (CCL) and the second run for the actual perforation. The underbalanced condition calculated based on wellbore fluid displacement is often deemed insufficient to create effective cleanup of the perforations.

This paper outlines a solution to these challenges. For a CT perforation campaign in the South China Sea, a CT string equipped with fiber optic cable inside was used, coupled with a bottomhole assembly capable of measuring both bottomhole temperature, internal and external CT pressure, and in addition casing collar locator. The primary objective of the job was to ensure that the perforation was performed with maximum under-balance but not exceeding a safe drawdown on the formation and risking collapse of the perforation tunnels. With 1,000 psi initial underbalance, to remove perforation damage the well would then remain balanced to avoid fluid invasion on the new perforations. The secondary objective was to avoid an additional CT run for correlation, thus saving rig time.

The objectives were met and this new approach to coiled tubing operations was found to be effective. Not only was there significant saving of rig time, the wells performed superior to existing wells and were brought into production sooner than planned. This technology has elevated CT standard operation onto a higher level in Malaysia.
Solving Excessive Water Production in a Prolific Long Horizontal Open Hole Drilled in a Naturally Fractured Carbonate Reservoir
Authors: Lightford Stephen , Pitoni Enzo , Burrafato Giovanni , Serapiglia Claudia Porretta
Published: April 2008

The paper presents a case history of a successful operation that was performed to reduce excessive water production in a horizontal well drilled through a naturally fractured carbonate reservoir. Because the well was completed with a 940-m horizontal openhole section, there were two significant issues in the attempt to reduce water cut without the use of a workover rig. There was no practical means of selectively isolating sections of the open hole, and even if it could be achieved, the fractures producing water could not be identified and individually isolated.

A treatment was performed employing a sealant that would set up only in presence of water and would remain fluid in anhydrous conditions. This sealant was placed using a coiled tubing unit (CTU) and then overdisplaced into the formation, into the natural fracture system.

Before the treatment, this naturally flowing prolific oil producer would not flow because of the hydrostatic pressure from the excessive water cut (i.e., >60%). Following the treatment, the well flowed at approximately 20% water cut for a few days, stabilized at 40%, and has remained in natural flow since the treatment.

This paper describes the philosophy behind the treatment design, the testing of the sealant, the placement procedure, subsequent well operations, and well performance. To re-establish this well into productive natural flow without the use of a workover rig was considered to be a significant success, and the long-lived effectiveness of the treatment has exceeded expectations.
Use of 3D Laser Imaging for Inspection of Coiled Tubing
Authors: Christian Amitkumar , Tipton Steven M. , Emnett Amanda R.
Published: April 2008

Current coiled tubing (CT) inspection technology is based predominantly on magnetic flux leakage (MFL). This approach is useful for detecting flaws on both the outer and inner surface of tubing. However, MFL is currently incapable of consistently providing information about the geometry of the flaw, which is adequate to assess its influence on fatigue endurance.

The use of 3D laser imaging has demonstrated the potential to detect flaws, but more importantly, to completely characterize their geometry. With the full three-dimensional mapping of the defect surface, critical defect parameters can be computed. For example, the system provides immediate information about the depth, length, width and projected surface area with a high degree of accuracy. Additionally, other features can be extracted from the laser images, including the volume of the defect and the notch root radius, which could be used to refine quantitative estimates of the flaw's severity.

Promising results from prototype systems are presented. A CT specific tool is being developed to scan known defects, detected visually or with existing inspection technology, and compute their influence on remaining fatigue life. This could serve as the basis for the development of stand-alone laser-based CT inspection systems. Additionally, a system has been developed that is capable of passing through coiled tubing in order to characterize flaws on its inner surface.
Expanding the Use of Turbodrills in Coiled Tubing and Workover Applications
Authors: Grigor Charlie , Conroy Dave , Henderson Marc
Published: April 2008

With the ever increasing demands placed on downhole tools with well reaching deeper depths, increasing bottomhole temperatures, and reduced bottomhole pressures these hostile environments place increasing demands on the tool providers to supply tools that will withstand these ever increasing demands. One way to overcome these demands is to utilize a purely metallic drilling tool such as a downhole Turbodrill. The turbine power section and bearing section are constructureed with only metallic components eliminating the requirement for elastrometic stators, which have proven problematic, when bottomhole temperatures reach or exceed the rated temperatures or nitrogen is required to ensure well integrity.

Traditionally turbodrills have been utilized for the most extreme high pressure and/or high temperature, hard rock-drilling applications – this paper will expand on some of the latest improvements to the tool design such as blade design which has enabled the tool length to be reduced allowing easier rig up for coiled tubing applications. Testing of the tools as well as case histories are included, that will illustrate that the Turbodrills can be used as successfully in challenging drilling and work-over applications.
Improved System for Accessing Multilateral Wells in Canada
Authors: Harber B. , Stuker J. , Pipchuk D.
Published: April 2008

In the past, the operational and cost concerns of being able to treat and evaluate multilateral wells have left operators with limited economical options for remediation and evaluation. This paper describes a combination of fiber optic-enabled measurement system and a selective multilateral reentry tool.

The new system’s bottomhole assembly design includes a multilateral reentry tool and real-time bottom hole feedback. The live feedback provides the operator with constant tool position in the wellbore which can serve as a key indicator of downhole tool function. With these specific measurements, downhole CT operations can be tracked and analyzed more quickly and clearly than ever before. Furthermore, this constant stream of critical data arms the onsite engineers and operators with information to make immediate decisions and thereby increase overall intervention efficiencies.

This paper demonstrates how this system has been effectively used during stimulation services for openhole multi lateral wells in Canada.
Fiber Sweeps for Hole Cleaning
Authors: Ahmed R. M. , Takach N. E.
Published: April 2008

Cuttings transport in highly deviated wellbores is more challenging and critical than in vertical wells. In inclined wells, the fluid velocity has a reduced vertical component that may not be sufficient to transport all the cuttings to the surface. When cuttings returns do not appear to be sufficient for the drilling rate, hole cleaning sweeps are applied to clean the borehole or reduce cuttings bed thickness. Fiber-containing sweeps have been very effective in cleaning highly deviated and extended reach wells. In addition, substantial torque and drag reduction has been reported when fiber-containing drilling fluids are used in the field. Although field observations are encouraging, currently very little is known about flow behavior, hydraulics and cuttings transport efficiency of fiber sweeps.

There is a great need for understanding how fiber particles enhance the cleaning capabilities of fiber-containing sweeps. The interaction between fiber particles and drilling fluid is still not fully understood, although the improvement in cuttings and solids transport is attributed to the formation of a fiber mat/network that enhances the carrying capacity of drilling fluids.

This article presents results of experimental investigations conducted to study hole-cleaning performance of a fiber sweep. Flow loop experiments have been carried out to evaluate and compare sweep efficiencies of the fiber sweep (0.47% Xanthan Gum and 0.04% synthetic fiber) and the base fluid (0.47% Xanthan Gum). Equilibrium bed heights were measured at different sweep flow rates in horizontal and inclined configurations. Results from this study indicate that a fiber-containing sweep has better hole cleaning capabilities than the base fluid, even though these two sweep fluids have very similar rheological properties. Moreover, adding fiber slightly reduces friction pressure loss under turbulent flow conditions.
Intervening With Coiled Tubing Through the Tubing-Casing Annulus to Restore Well Control
Authors: Sonnier Baine , Sackash Mark
Published: April 2008

It is common for coiled tubing (CT) to be sent to rigs to circulate kill-weight fluid when a rig has lost well control. This is a safe, effective means of regaining the well-control barrier so that normal rig operations can resume. Occasionally the rig is not able to simply shut in at surface while coiled tubing is being delivered, leading to closing of the rig's blind shears. In such cases, coiled tubing intervention is less common.

This paper discusses a situation that developed off the coast of Louisiana in which primary well control was lost, forcing the rig being used in a workover operation to close its blind shears on a dual-tubing string. The resulting situation left 4,175 psi pressure at surface and 9-lb/gal fluid in the well. Coiled tubing was then run into the tubing-casing annulus to 9,250 ft and 16.5-lb/gal fluid was circulated down the coiled tubing and out the casing. This paper discusses the prejob modeling, operation, and outcome of this work.
Entering Multilateral Wells Using Coiled Tubing
Authors: Proctor Robert , Grant Ryan , Marron Andrew , Cubas Danny
Published: April 2008

Coiled tubing is utilized to enter horizontal wells for the purpose of performing general remedial well operations. Common operations performed include but are not limited to stimulation treatments, solvent treatments, cleanouts and water shut-off. In today's oilfield, many horizontal well plans incorporate the drilling of multiple laterals. Entering multiple laterals, in one well, using coiled tubing, requires guidance. Advanced completion designs may facilitate such guidance. However, in the case of open hole multi-lateral wells a guidance system is not incorporated in the completion design. This paper will discuss a reliable commercially available technology, developed for the purpose of entering open hole multilateral wells using coiled tubing. The paper will review bottom hole assembly functionality, development of this technology and applications. In addition, offshore case histories of wells entered using multi-lateral entry guidance technology will be summarized.
Efficient Offshore Scale Removal Without a Rig: Planning, Logistics, and Execution
Authors: Guimarães Zacarias , Almeida Victor , Duque Luis H. , Pinto Julio C. , Coutinho Sandro , Chagas José V. , Costa Giovani V. , França Alessandro B. , Gouveia Manoel , Peixoto Cristóvão , Teles Carlos A.
Published: April 2008

Although the oil industry seeks to increase the worldwide production of hydrocarbons, various well and reservoir problems can severely reduce oil and gas production from individual wells, leading to the requirement for intervention. For example, in mature fields offshore Brazil, production platforms with minimal open work space and without workover rigs have been a challenge for restoring production in wells with serious scaling problems. The scale build-up reduces production, month by month, until a rig has to be mobilized to replace the production string.

Trying to recover production efficiently, service and operating companies have been presenting solutions that circumvent the practical limitations of these locations.

In the last three years, an operator's engineering department has worked with service company engineers to develop the means to rig up a 1-3/4-in., 4500-m-long coiled tubing string in a work area of 234 sq. meters and with a crane with a 12-ton maximum capacity. This cooperation allowed intervention in wells on rigless platforms, reducing working time, environmental impacts and costs.

These interventions helped to increase oil production from Field A in the Campos Basin and gas production from Field B in the Santos Basin, currently the most important gas field offshore Brazil.

Both fields suffer from severe scale deposition -- barium sulfate in Field A and calcium carbonate in field B -- which builds up in the production string and effectively reduces the internal diameter, consequently reducing production.

The new successful interventions in these fields using rigless coiled tubing and scale removal techniques enhanced the hydrocarbon production from these fields.

In Field A (oil production), interventions were performed in seven (7) wells, providing around a 40% increase in production.

In Field B (gas production), interventions were performed in five (5) wells, providing a production increase of around 27% per day.

This paper details the planning, logistics and techniques used to successfully meet both challenges. The same solutions would apply in other fields around the world where platform space and scarcity of rigs limit an operator's ability to remediate scale or other wellbore problems that constrain hydrocarbon production.
New Electro-mechanical Perforating Technology Reduces Cost and Increases Safety in Workover Operations
Authors: Bargawi Riyadh A. , Dean Doyle , Clemens Jack , Whitmire Clem
Published: April 2008

Saudi Arabia wells, onshore and offshore, often require workovers as a result of the corrosive environment to which the downhole equipment is subjected. When the workover jobs required a single hole to be punched in "soft" tubing using traditional methods, high failure rates and inherent delays in mobilizing explosives often severely compromised job economics.

This paper presents several case histories in which a new slickline-deployed electro-mechanical tubing punch was used for the first time worldwide. Although the workover requirements in each well were different, and the jobs were conducted in both onshore and offshore environments, all required a single hole to be drilled.

The case histories will discuss the advantages provided to the operator through use of the new electro-mechanical tubing punch. These included: 100% perforating reliabilityReduced rig time by eliminating mobilization of explosives and other equipment, if failures occurred.Reduced costs, since electro-mechanical perforating is more cost effective than electric-line "soft-shot" methodsApplicability to deployment on slickline, E-line, or coiled tubingSimplicity in use of the electro-mechanical perforatorEnhanced personnel and environmental safety from: Elimination of explosivesUse of alkaline or lithium batteriesUse of mono-conductor lineUse of CTU pressure-switch adapter

The new method was 100% successful and resolved the problems experienced with all previously used conventional mechanical perforating methods. Although run in highly corrosive downhole conditions, the perforating tool had 100% success in perforating the "soft" tubing. A thorough follow-up inspection of the tool showed that it had sustained no damage of any kind.

An in-depth discussion concerning the electro-mechanical perforator design, its application in Saudi Aramco wells, its operational advantages, and its significant impact on safety and economics will be presented.
Field Experience Using an Intervention Wellhead Structure Modeling and Monitoring System
Authors: Newman Ken , Smalley Ed , Linares Lionel , Kelleher Patrick
Published: April 2008

A case history of an attempted CT intervention in 43' of water through a wellhead leaning at a 45 degree angle is presented. A major concern for this intervention was the integrity of the intervention stack between the leaning wellhead and the CT injector located on a lift boat. The stack design, testing and stack performance during the job execution are presented.
Deepwater Isolation Valve Contingencies Using E-Line Stroking Tool
Authors: Schwanitz B.
Published: April 2008

Many subsea completions employ a down hole isolation valve for temporarily closing off production while awaiting first oil or flow line connections. These valves are designed to be opened or closed through surface pressure pulses in the fluid column to activate stored nitrogen in the valve housing. When a valve fails to activate as expected, a reliable contingency plan must be ready or the financial consequences can be large.

With the use of electric wireline tractor technology, a contingency valve opening system allows malfunctioning isolation valves to be mechanically shifted with depth precision and controlled force. This method uses an electrically powered hydraulic stroking tool to shift the valve sleeve open or closed with a selected force of 10K - 30K lbs depending on the type of valve. The stroking tool is either tractor conveyed in high angles or run with only a shifting tool attached in low angles. A new intelligent key tool replaces the spring loaded shifter, to allow the system to be run "slick" and avoid hang ups on down hole profiles that can occur with the conventional spring loaded shifting tools.

An electric line deployed solution is faster to mobilize, more precise in locating shifting sleeves and less expensive than alternative solutions. A review of case histories will prove these points. Also, pre-job planning, integrated team involvement, SIT and operational recommendations will be discussed.
HP/HT WCCL Technology Aids Successful Deployment Perforating Operations on the Glenelg Field
Authors: Gordon William , Pittman Iain , Rydlewicz Mervyn , Innes Richard
Published: April 2008

This paper describes the results obtained as well as the equipment and techniques used on the Glenelg field in the UK central North Sea (CNS) to perforate and complete a new high-pressure high-temperature (HPHT) production well.

This paper begins by discussing the types of equipment required for HPHT coiled-tubing (CT) intervention. This includes the front-end engineering for the hottest, deepest, highest pressure, and most deviated well produced from, to date, in the UK CNS. This paper discusses the CT string design, as well as the selection of downhole tools, for temperatures above 400°F. The CT intervention, wireless casing collar locator (WCCL), depth correlation, and perforating operations are presented. This is the hottest environment in which WCCL technology has been successfully applied worldwide.

The lessons learned during this project, together with the results from this case history, are presented. Conclusions are drawn about moving forward with both the WCCL technology and conducting similar operations.
Cleanouts With Coiled Tubing in Low-Bottom-Hole Pressure Wellbores
Authors: Li J. , Luft H. B. , Wilde G. , Alingig G. , Jumawid F.
Published: April 2008

Cleaning debris from a wellbore is a common operation with coiled tubing (CT). Considering that this process is a complex function of fluid properties, flow velocities, hole size, deviation angle and particle properties, it becomes particularly challenging in wells with low bottom hole pressures (BHP).

There are two circulation modes involved in conventional sand cleanouts with CT, namely forward and reverse circulation. Either sand cleanout method may apply excess hydrostatic pressure on the formation that can result in loss of circulation and returns, hence making cost effective solids removal impossible as well as potentially damaging the formation. In conventional cleanouts, nitrogen or low density hydrocarbon fluids can be used to reduce hydrostatic pressure; however this necessitates a very careful job design and execution which can require expensive volumes of nitrogen (N2) or hydrocarbon fluids. An alternative technology that combines a concentric coiled tubing (CCT) string with a down hole jet pump to remove solids from a wellbore but without placing any additional hydrostatic pressure on the formation has also proven to be remarkably successful.

This paper reviews these different solids cleanout methodologies and summarizes the advantages and limitations related to each method when used in low formation pressure wellbores. New solids transport flow loop test results, related to a hydrocarbon fluid, are summarized and compared with tests using water. Case histories are presented that demonstrate how to select the most appropriate cleaning method based on well conditions.
Successful Offshore Application of Acid Tunneling Technology: Overcoming the Difficulties of High Depths, Temperatures, and Deviations
Authors: Alonso Perex Luis Angel , Diaz Jose Daniel , Navarro Manuel , Moss Paul , Curtis James
Published: April 2008

Field applications of acid tunneling technology began in late 2005 in the Mara Field of Western Venezuela as an alternative to both initial new well stimulation and producing well maintenance. In this field, acid tunneling is used to treat sections of formation in an open hole completion that have been severely damaged from invasion of muds, cements and/or fluid loss control material in an attempt to interconnect the microfractures present in dual porosity carbonate formations. Since the initial trial, thirteen wells have been successfully treated with this technique; obtaining long term production increases. The large majority of wells situated in the Mara Field exhibit the same two primary conditions: shallow average depths around 6000 ft and temperatures around 200 °F. A logical step in the development process of this technique would be to successfully apply the process in areas outside of Venezuela and with more stringent wellbore conditions.

This paper outlines the operational procedures and subsequent results from the successful implementation of the acid tunneling process in an offshore, open hole completed well located on the Casablanca Platform in the Mediterranean Sea, offshore Spain. A hydraulic kick-off tool and a specially designed jetting assembly were deployed on coiled tubing to create a single lateral hole in a carbonate reservoir using hydrochloric acid as the treatment fluid. This was the first implementation of the acid tunneling process outside of Venezuelan borders. It was also the first application in a well with a depth greater than 7,000ft and a bottomhole temperature greater than 200 °F. Finally, it marked the first time the process was used on an offshore well. The well characteristics, the operational procedures, and the improvements made to the acid tunneling tools for this project are discussed.
Wireline Deployed Metal Sealing Bridge Plug System: Operational Learning Curve and Subsequent Redevelopment
Authors: Chapman I. C. , Ng K. S. , Nor N. M. , Mackenzie G. R. J. , Garfield G. L.
Published: April 2008

This paper will focus on a project to redevelop a wireline deployable metal-to-metal seal, ISO 14310 VO qualified, retrievable bridge plug system to allow it to be conveyed successfully in a high rate gas well for acid stimulation zonal isolation operations. Functionality of the original system including the plug and hydrostatic setting assembly had previously been tested in a fluid environment yet envisioned for a gas well application. Initial well installations gave results that led to a reconsideration of the forces being generated by the running and pulling tools due to the differences between a gas and a fluid environment and their impact on system reliability and functionality. The paper will discuss some of the problems discovered with the system for this particular application and the system redesign over a one-year period, which included a number of qualification tests performed at near to real well conditions. This discussion will include information on the complexities of performing such tests and the solutions used to develop a successfully qualified "fit-for-purpose" redesign. The paper will conclude with a high-level overview of the system's first deployment in an actual field well application.
Evaluation of induction characteristics and hypnotic potency of isoflurane and sevoflurane in healthy dogs
Authors: Hofmeister Erik H. , Brainard Benjamin M. , Sams Lisa M. , Allman David A. , Cruse Ashley M.
Published: April 2008

Objective—To determine induction characteristics and the minimum alveolar concentration (MAC) at which consciousness returned (MACawake) in dogs anesthetized with isoflurane or sevoflurane.

Animals—20 sexually intact male Beagles.

Procedures—In experiment 1, 20 dogs were randomly assigned to have anesthesia induced and maintained with isoflurane or sevoflurane. The MAC at which each dog awoke in response to auditory stimulation (MACawake-noise) was determined by decreasing the end-tidal concentration by 0.1 volume (vol %) every 15 minutes and delivering a standard audible stimulus at each concentration until the dog awoke. In experiment 2, 12 dogs received the same anesthetic agent they were administered in experiment 1. After duplicate MAC determination, the end-tidal concentration was continually decreased by 10% every 15 minutes until the dog awoke from anesthesia (MACawake).

Results—Mean induction time was significantly greater for isoflurane-anesthetized dogs (212 seconds), compared with the sevoflurane-anesthetized dogs (154 seconds). Mean ± SD MACawake-noise was 1.1 ± 0.1 vol % for isoflurane and 2.0 ± 0.2 vol % for sevoflurane. Mean MAC was 1.3 ± 0.2 vol % for isoflurane and 2.1 ± 0.6 vol % for sevoflurane, and mean MACawake was 1.0 ± 0.1 vol % for isoflurane and 1.3 ± 0.3 vol % for sevoflurane.

Conclusions and Clinical Relevance—Sevoflurane resulted in a more rapid induction than did isoflurane. The MACawake for dogs was higher than values reported for both agents in humans. Care should be taken to ensure that dogs are at an appropriate anesthetic depth to prevent consciousness, particularly when single-agent inhalant anesthesia is used.
Cyclooxygenase expression and prostanoid production in pyloric and duodenal mucosae in dogs after administration of nonsteroidal anti-inflammatory drugs
Authors: Wooten Jenna G. , Blikslager Anthony T. , Ryan Kathleen A. , Marks Steve L. , Law J. Mac , Lascelles B. Duncan X.
Published: April 2008

Objective—To assess cyclooxygenase (COX) expression and prostanoid concentrations in pyloric and duodenal mucosae of dogs after administration of nonsteroidal anti-inflammatory drugs (NSAIDs).

Animals—8 healthy dogs.

Procedures—Each dog received carprofen (4.4 mg/kg, q 24 h), deracoxib (2 mg/kg, q 24 h), aspirin (10 mg/kg, q 12 h), and placebo (1 dog treat, q 24 h) orally for 3 days (4-week interval between treatments). Before study commencement (baseline) and on day 3 of each treatment, pyloric and duodenal mucosal appearance was assessed endoscopically and biopsy specimens were obtained for histologic examination. Cyclooxygenase-1 and COX-2 protein expressions were assessed via western blotting, and prostanoid concentrations were measured via ELISAs. An ANOVA was used to analyze data.

Results—Treatments had no effect on mucosal appearance and ulceration was not evident histologically. In pyloric and duodenal mucosae, COX-1 expression was unaffected by treatments. Cyclooxygenase-2 expression remained unchanged in pyloric mucosa; in duodenal mucosa, aspirin significantly increased COX-2 expression, compared with effects of deracoxib and carprofen. At baseline, total prostaglandin and thromboxane B2 concentrations in pyloric mucosa were significantly greater than those in duodenal mucosa. Aspirin significantly decreased both prostanoid concentrations in both mucosal tissues, compared with other treatments. In pyloric mucosa, carprofen administration significantly decreased total prostaglandin and thromboxane B2 concentrations, compared with deracoxib administration.

Conclusions and Clinical Relevance—In dogs, prostanoid synthesis was greater in pyloric mucosa than it was in duodenal mucosa. Nonselective NSAIDs significantly decreased prostanoid concentrations in these mucosae, compared with the effects of a selective COX-2 NSAID.