Casing String Research Articles

Dynamic Response of High-Pressure Riser of Deepwater SBOP System

The application of surface blowout preventer (SBOP) drilling system in deepwater environments has been demonstrated that it can save operation cost and time. The high pressure small diameter casing plays the role of the conventional riser and bears the complex loading caused by the wave and current force and drilling platform motion. The coupled quasi-static and uncoupled dynamic analysis models of deepwater SBOP drilling system were established. The analysis results indicate that the uncoupled method without consider the lateral offset on the end of the high pressure riser nearly no affection to the riser analysis. However, the uncoupled method has a certain impact on the mechanical analysis of the subsea wellhead and the casing string under mudline. The lateral offset of the high pressure riser changes greatly in the different times, the bending moment of the upper and lower stress joint of riser is bigger. The platform long-term drift has a greater impact on the dynamic response analysis of the high pressure riser of SBOP system for deepwater drilling. DOI: http://dx.doi.org/10.11591/telkomnika.v10i4.858

Casing While Drilling (CwD): A New Approach To Drilling Fiqa Formation in the Sultanate of Oman—A Success Story

SummaryHighly reactive Fiqa shale used to compel well engineers in the Sultanate of Oman to plan drilling phase of surface and intermediate sections primarily based on time exposure to aqueous drilling fluid water-based mud (WBM). The new approach of drilling the time-dependent Fiqa formation using casing-while-drilling (CwD) allows well engineers to plan prospective top/intermediate wellbore sections differently by enhancing the overall drilling performance. This reduces the risk of setting casing strings at unplanned depths, getting pipe stuck, or reaming continuously when drilling with conventional drillstring. The technical feasibility study, risk assessment, planning, execution, and the lessons learned during the process of drilling two top-section pilot projects are described in this document. The CwD team compares the drilling performance of several offset wells and suggests actions to improve the CwD technology in Oman.Two 17½ - and 22-in. surface sections were drilled successfully with large-diameter casing strings and reached 754- and 894-m measured depths, respectively. The implementation of the CwD concept reduced the overall drill/case phase time up to 40%, in comparison with the average using conventional drilling in those fields. Exposure time of Fiqa to aqueous environment was reduced by eliminating conditioning trips and nonproductive-time (NPT) associated with wellbore instability. Drilling both sections with non-retrievable 17½×13⅜-in. and 22×18⅝ -in. CwD systems did not require modification of well design or rig. The optimization of this technology will support its implementation as the conventional drilling approach in some fields in Oman.

Dynamic Response of the Casing String in Seabed Soil for Deepwater Drilling

The marine riser has transfer dynamic cyclic load to the top of casing string when deepwater drilling operating. Considering with the nonlinear characteristics of seabed soil, the variable string cross section, and the axial load on the top of string, a dynamic differential equation of casing string below mud line and its numerical solution were established. Results illustrate that, the lateral displacement, the bending moment, and the shear of the casing string are not equal when lateral dynamic cyclic loading achieves amplitude due to the soil hysteresis effect. The diameter and wall thickness of conductor have less affect to string vibration frequency, cannot adjust the string natural frequency by adjusting these parameters. The natural frequency of casing string in sand is bigger than it in clay. The undrained shear strength of soil has great effect on the natural frequency of casing string in clay. The lateral displacement amplitude is highest when the vibration frequency of casing string at its natural frequency.

IODP Expedition 328: Early Results of Cascadia Subduction Zone ACORK Observatory

Abstract. Integrated Ocean Drilling Program (IODP) Expedition 328 was devoted to the installation of an Advanced CORK (Circulation Obviation Retrofit Kit) in the Cascadia subduction zone accretionary prism to observe the physical state and properties of the formation as they are influenced by long-term and episodic deformation and by gas hydrate accumulation. Pressures are monitored at four levels on the outside of a standard 10 3/4-inch casing string, two above and two below the base of the gas-hydrate stability zone at 230 mbsf (m below seafloor). The casing was sealed at the bottom, leaving the inside open down to 302 mbsf for installation of a tilt meter, seismometer, and thermistor cable (scheduled for 2013). The initial data, recovered in July 2011, document an initially smooth recovery from the drilling perturbation followed by what may be a sequence of hole-collapse events. Pressure at the deepest screen is roughly 40 kPa above hydrostatic; higher pressures (80 kPa) are observed at the two screens close to the level of hydrate stability. Tidal variations at the deepest screen are in phase with ocean tides, and define a loading efficiency of 0.6, which is reasonable in light of the consolidation state of the for-mation (porosity ~0.5). Tidal signals near the level of gas hydrate stability display large phase lags, probably as a consequence of hydraulic diffusion stimulated by the large contrast in interstitial fluid compressibility at the gas-hydrate boundary. The degree of isolation among the screens, the anticipated good coupling, and the estimated strain-to-pressure conversion efficiency (~5 kPa μstrain−1) indicate that this installation will serve well to host a variety of hydrologic, seismic, and geodynamic experiments. doi: 10.2204/iodp.sd.13.02.2011

IODP Expedition 328: Early Results of Cascadia Subduction Zone ACORK Observatory

Integrated Ocean Drilling Program (IODP) Expedition 328 was devoted to the installation of an "Advanced CORK" (Circulation Obviation Retrofit Kit) in the Cascadia subduction zone accretionary prism to observe the physical state and properties of the formation as they are influenced by long-term and episodic deformation and by gas hydrate accumulation. Pressures are monitored at four levels on the outside of a standard 10 3/4-inch casing string, two above and two below the base of the gas-hydrate stability zone at 230 mbsf (m below seafloor). The casing was sealed at the bottom, leaving the inside open down to 302 mbsf for installation of a tilt meter, seismometer, and thermistor cable (scheduled for 2013). The initial data, recovered in July 2011, document an initially smooth recovery from the drilling perturbation followed by what may be a sequence of hole-collapse events. Pressure at the deepest screen is roughly 40 kPa above hydrostatic; higher pressures (80 kPa) are observed at the two screens close to the level of hydrate stability. Tidal variations at the deepest screen are in phase with ocean tides, and define a loading efficiency of 0.6, which is reasonable in light of the consolidation state of the for-mation (porosity ~0.5). Tidal signals near the level of gas hydrate stability display large phase lags, probably as a consequence of hydraulic diffusion stimulated by the large contrast in interstitial fluid compressibility at the gas-hydrate boundary. The degree of isolation among the screens, the anticipated good coupling, and the estimated strain-to-pressure conversion efficiency (~5 kPa μstrain<sup>−1</sup>) indicate that this installation will serve well to host a variety of hydrologic, seismic, and geodynamic experiments. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.13.02.2011" target="_blank">10.2204/iodp.sd.13.02.2011</a>

Stress Analysis of Internal Wall Worn Casing String under Uniform Earth Pressure Based on ANSYS

Wear of casing string is a common phenomenon in the process of oil and gas exploitation, and it reduces collapse and burst strength of casing string. Stress of internal wall worn casing string must be analyzed to ensure strength of casing string. In the paper, wear form of casing string is assumed as a crescent-shape, and a half finite element model (FEM) of worn casing string, cement-loop and earth combined system is established using the symmetry. Geometry relationships of wear ratio (or wear depth) and the centre of drill pipe are established. Effects of variables such as wear ratio of casing string, magnification factor of wellbore, elastic modulus of cement-loop and working conditions on casing string stress are discussed respectively. Some conclusions are drawn: maximum stress in casing string increases with increased wear ratio of casing string, and ultimately exceeds the yield limit. Increase of magnification factor of wellbore will improve bearing capacity of casing string, but maximum stress in casing string decreases slower and slower with further increase in magnification factor of casing string, at the same time, stress decreases more in casing string than in cement-loop. Minimum stress in cement-loop increases and maximum stress in cement-loop fluctuates with increased elastic modulus of cement-loop, while both minimum and maximum stress in casing string first increases then decreases, the turning point is related to elastic modulus of casing string and earth, as well as the geometry relationships among them. The bigger pressure difference, the larger maximum stress exists in casing string.

Kick-Tolerance Misconceptions and Consequences for Well Design

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 140113, ’Kick-Tolerance Misconceptions and Consequences for Well Design,’ by Helio Santos, SPE, Erdem Catak, SPE, and Sandeep Valluri, Safekick, prepared for the 2011 SPE/IADC Drilling Conference and Exhibition, Amsterdam, 1-3 March. The paper has not been peer reviewed. Kick tolerance defines the appropriate number and setting depths of casing strings required to achieve drilling objectives. It also is used during drilling to determine whether it is safe to continue drilling or if there is a need to run a casing string. Alternatively, it is used to indicate whether it is safe to circulate a kick out of the well or whether bullheading is necessary. During development of a new well-control system, a thorough review of the fundamental concepts involved was carried out, and, in relation to kick tolerance, a few misconceptions were identified. Introduction Even though kick tolerance is a critical and fundamental concept for the drilling industry, there is no standard used by operators, drilling contractors, or training institutions. Hence, there are several definitions of kick tolerance and different ways of calculating it. This lack of consistency may be why the subject is not well understood and, there-fore, is sometimes used dangerously. Definitions of kick tolerance may be in terms of pit gain, mud-weight increase, or underbalance pressure. Another point of disagreement is on how the predicted pore pressure should be used in calculations. Some companies use a value greater than the mud weight, while others use a value greater than the predicted pore pressure. Despite the variations, the goal is consistent: to use a procedure that ensures safe drilling of a well. Often, this lack of a standard and of under-standing the topic leads to uncertainty and discussions during drilling. Questions often arise regarding whether it is safe to continue drilling. Because wells are now drilled in more-challenging environments, such as high-pressure/high-temperature and deep and ultradeep water, a small variation in the way that kick tolerance is calculated can lead to premature abandonment of the well or, worse, to a hazardous drilling situation. Kick-Tolerance Calculation—Current Approach The first step of a simplified kick-tolerance calculation (i.e., constant temperature, constant density, and no compressibility) is to define the maximum vertical height of a gas influx Hmax at the casing shoe (assumed to be the weakest point in the open hole). Hmax is deter-mined on the basis of fracture gradient; mud weight; kick-fluid density; predicted pore pressure; and adjusted maximum allowable annular surface pressure (MAASP), which is reduced by a safety margin. What is conceptually wrong is that if the bottomhole-assembly (BHA) length is greater than Hmax, the kick cannot be circulated out of the wellbore because it will reach the top of the drill collars with a kick height greater than Hmax, which would induce losses at the shoe.

Evolution From Casing Running to Assurance of Total Depth

Technology Update Well construction, hazard mitigation, and drilling equipment have evolved significantly over the past 10 to 15 years. One of the most critical aspects of well construction is assuring that casing strings are installed to the planned depth with gas-tight connections and sound mechanical barriers between them. The widespread acceptance of top drive casing running and drilling with casing have played a key role in recent developments to the delivery of high-integrity casing strings. Top drive casing running tools attach to the rig’s top drive and combine many conventional casing tools into one sys-tem. They extend the functionality of the rig’s top drive from drill pipe to casing, thus enabling simultaneous rotation, reciprocation/push down, and circulation of the casing string. Adding a reaming shoe or drillable casing bit to the casing string makes it possible to ream in a pre-drilled section, extend through problem zones or drill complete hole sections with the casing string. This addition opens a broad range of options to increase drilling efficiency and reduce nonproductive time. Technology Expands Top Drive Applications Top drive casing running systems first came into use in the 1990s. Initially, these systems were used primarily on purpose-built casing drilling (land) rigs. Soon after early deployments, the technology became an accepted way to run casing. However, its use was still limited to land rigs and running API threaded tubulars. By 2005, further development of the technology portfolio included equipment designed to accommodate a broad range of applications such as: Offshore rigs—casing sizes up to 22 in., torque up to 80,000 lbf-ft Premium connections—independent torque monitoring and active weight compensation Heavier casing strings—hoisting capacity up to 750 tons Running casing in stands—interfacing with pipe handling and rig control systems High-angle and ultraextended-reach wells—pushing, rotating, and floating casing strings Chrome tubing completions—minimal marking systems and torque control interface During this time, the equipment for drilling with casing and casing connections also evolved, with the development of a number of drillable polycrystalline diamond compact casing bits and higher torque- and fatigue-resistant connections to cope with various formation strengths and geology. Today, these technologies are field proven in a number of applications and readily available across the globe. Thousands of casing strings have been run or reamed by means of the top drive system, and more than 2,000 problem zones or well sections have been successfully drilled with the casing string.

Cause Analysis of Buttress Premium Thread Connection Pullout for a Well

The buttress thread connection was used in deep well or ultra-deep well widely because of its high joint efficiency. Pullout failure scarcely happen on buttress premium thread connection with great joint strength and good sealing property. Direct evidences about connection dropout couldn’t get in most cases by reason of casing string had fallen into well or casing string had been concreted in formation by cement. Now the difficulty of analysis on pullout is higher and higher. A buttress premium thread casing joint had pulled out at mill end of coupling in a straight well and dropout casing string couldn’t get out of the well. Research on this pullout case was carried out combining relative theories with tests. Macroscopic analysis and dimension measurement were done for dropout coupling. The material’s physical and chemical properties were checked. Thread inspection and full-scale tests were done for two casing simples that are same lot with pullout. Metallograph analysis was carried out on load flank and guide flank in box thread of pullout coupling and same lot new coupling. The results showed that dropout failure was ascribe to inadequate make-up torque at mill end of pullout coupling and complex downhole condition and improper handling in the oil field. On the other hand joint’s strength decline on the effect of unsuitable heat treatment to coupling and greatly uneven black crested pin thread around circumference. The pertinence measures were laid down at the end of this passage.

Economy and Reliability Selection of Production Casing Thread Connections For Low pressure and Low permeability Gas Field

Abstract At present it is widely accepted that if gas reservoir pressure is more than 28 MPa, premium connections in production casing should be selected. However, the price of premium connections is about 1.5 to 2 times than traditional API round thread connections. Therefore, economy and reliability selection of casing thread connections type is one of effective measures to reduce development costs in low –potential gas field. Economy and reliability selection of casing thread connections type in sulige gas field (in China,Well depth at 3550 m, Gas reservoir pressure 35 MPa) was study. Through ϕ 139.7×9.17/7.72 mm N80/J55 LC casing gas-tight test under complex loads and statistical casing full-scale test data in past were analyzed, a minimum safety factor for casing string gas-tight design was determined by casing strength margin and reliability analysis method. Gas-tight reliability effect of load variability on casing was validated by Monte Carlo method. Two sets of casing string were successfully designed and applied to over 800 wells in the gas field, and all wells were reported running well until now. Over 4 hundred million Yuan(RMB) investment was reduced in developing these wells. Following conclusions were achieved by practice: Casing string of production using API long round thread and CATTS101 compound instead of premium connection was economical and feasible for low-pressure and low-permeability gas field development. Main effect factors on gas-tight with standoff and pitch were discoverer in full-scale test, which was different from the current standards on taper in evaluation of gas-tight performance. By statistics of full-scale test data in past, the casing string of design and check is a reliability method with advantage of economic and universal applicability.

Mechanical Stability Analysis of Subsea Wellhead for Deepwater Production to Earthquake Load

Subsea wellhead for deepwater production subjects to axial force, lateral force and bending moment under the seismic loading, the effect of subsea christmas tree and casing string’s gravity. Joint action of these forces makes it is possible that horizontal displacement exceeds the limitation and thus loses the stability. A mechanical analytical model of subsea wellhead for deepwater production is established on the basis of the pile foundation theories and material mechanics, the seismic load and behavior between casing string and formation are considered. The analyses on lateral displacement, angular distortion, bending moment and shear force show that the affection of lateral load is focus on the upper section of casing string, and the lateral displacement of subsea wellhead for deepwater production increases along with earthquake load and thus decreases stability. The stability improves notably with the increase of coefficient of soil reaction. Therefore it is necessary to obtain the on-the-spot geological data in shallow formation. The wellhead stability may be improved to different degrees by taking measures such as minimizing axial load, enhancing the conductor bending strenth, increasing the depth of the casing string in soil, reducing the outcropping length of the casing string.

Particle-Size Distribution Improves Casing-While-Drilling Wellbore-Strengthening Results

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 128913, ’Particle Size Distribution Improves Casing- While-Drilling Wellbore Strengthening Results,’ by R.D. Watts, SPE, M.R. Greener, SPE, S. McKeever, SPE, P.D. Scott, SPE and D. Beardmore, SPE, ConocoPhillips, originally prepared for the 2010 IADC/SPE Drilling Conference and Exhibition, New Orleans, 2-4 February. The paper has not been peer reviewed. The full-length paper describes the application of particle-size-distribution principles for determining materials to be added to the mud system during casing-while-drilling (CWD) operations. CWD has been demonstrated to stop or significantly reduce lost circulation and improve well-bore strength. The mechanism by which this improvement occurs is not well understood. Introduction If wellbore strengthening can be achieved systematically, then wells can be drilled in known loss areas without contingency strings of casing. In addition, in mature fields where producing horizons have altered pressures from either depletion or pressure maintenance, wells can be drilled with fewer casing strings. Sidetracks become economical because hole size can be preserved for an effective completion, and well costs are lowered by not using additional liners to reach the objective. By adding particles to the mud to fill in the particle-size distribution, losses to natural fractures were stopped while directional wells were drilled with casing in the Piceance basin of Colorado. Applying what was learned in a field trial of CWD in the Alaskan Tarn field, the openhole leakoff resistance was improved by 3.0 lbm/gal drilling with 7.0-in. casing in a 67° angled well. With this success, a four-well CWD campaign was executed with two wells drilled each in the Kuparuk and Tarn fields on Alaska’s North Slope. Results were positive for 7.0-. and 7.625-in. casings, but wellbore strengthening did not occur sufficiently in the 5.50-in.-casing trials. Annular clearance appears to be a critical component for success and is not yet fully understood. The results demonstrate that a significant improvement in fracture gradient can be achieved with the right clearance between the hole and the casing and the proper-sized particles added to the mud system. In addition, the amount of material added has been demonstrated to be as low as 2 lbm/bbl. With confidence that strengthening can be achieved to the levels of improvement demonstrated, wells can be evaluated with significant cost savings by eliminating casing strings and preserving hole size for completions or further drilling. Smear Effect The smear effect has been considered to be either a smearing and plastering of cuttings onto the wellbore wall or the increase in hoop stress around the wellbore resulting when a crack is formed and particles are forced into the gap, creating a wedge and thereby raising the effective fracture gradient. At Piceance, imaging logs taken in the overburden confirmed natural fractures with a radially averaged aperture of approximately 1.0 mm, and these could be correlated back to losses while drilling. Because CWD had stopped losses in these intervals, wellbore strengthening was believed to be the more likely mechanism.

Extreme-Lean-Profile Concept for Long Extended-Reach Multilateral Wells: Cerro Falcone 4 OR Well Case History

This article, written by Senior Technology Editor Dennis Denney, contains highlights of paper SPE 133127, ’The 'Extreme Lean Profile' Concept as a Crucial Technology for Multilateral, Long, Extended-Reach Wells: The Case History of Cerro Falcone 4 OR,’ by A. Burini, SPE, R. Poloni, P. Valente, G. Cavallaro, and L. Mattioli, Eni E&P, prepared for the 2010 SPE Annual Technical Conference and Exhibition, Florence, Italy, 19-22 September. The paper has not been peer reviewed. Following many successful applications of the “lean profile” (LP) technique, a further step toward production maximization with a simultaneous increase in operational safety and a decrease in overall drilling cost has been achieved with the “extreme lean profile” (XLP). Compared with a conventional profile, the LP allowed running an additional casing between the 185/8- and 133/8-in. strings. The XLP introduces an additional casing between the 133/8- and 95/8-in. strings. Introduction A focus in the industry is achieving operational efficiency and production optimization while, simultaneously, safeguarding the environment. Hydrocarbon resources often are found in highly sensitive areas, and the capability of minimizing the effect on the natural environment could make the difference between obtaining permits and having such areas restricted. Excellent examples of technologies that enable these objectives are extended-reach drilling (ERD), multilateral drilling (MLD), and their combination, as in the case of Eni’s Cerro Falcone 4 Or well in the Val d’Agri field in Italy. Reservoirs that benefit most from MLD and/or ERD technologies include the following. Low-permeability and thin reservoirs Heavy-oil reservoirs Coalbed-methane resources Shale-gas basins Reservoirs prone to coning of undesired fluids However, drilling and completing extended-reach and multilateral wells pose operational challenges that must be overcome. The main challenges of ERD are the capability of Reaching the target and ensuring proper hole positioning relative to the reservoir, in consideration of the long distances involved. Providing a straight smooth borehole to drill the horizontal section to the maximum reach, and to reduce the risk inherent in casing-running operations. Ensuring a high drilling performance to prevent possible hole instability, which may be caused by the extended openhole drilling times, and to not compromise hole cleaning. For MLD, additional challenges include Exiting the main bore safely and efficiently with the required borehole size. Achieving the right degree of junction isolation. “Roadmap” to the XLP An accepted custom of conventional drilling is to run the surface and intermediate casings in holes that are up to 6 to 7 in. larger than the casing outside diameter (OD). This method is based on the difficulty of drilling a straight smooth borehole with conventional technologies and the stiffness of large-diameter casing strings hindering reaching the planned setting depths. The clearance between casing and open hole is reduced to approximately 1 in. for the deeper sections with more-flexible strings.

You've Got Mail (2010)

You've Got Mail (2010)

Thermally stimulated “runaway” downhole flow in a superhydrostatic ocean crustal borehole: Observations, simulations, and inferences regarding crustal permeability

An array of boreholes, drilled through a regionally continuous hydrologically confining layer of sediments into extrusive igneous basement rocks of the Juan de Fuca Ridge eastern flank, has been instrumented with CORK hydrologic observatories for long‐term monitoring and fluid sampling. Omission of seals between nested casing strings reaching into basement at one site created a low‐resistance connection between basement and the overlying water column, and despite the natural superhydrostatic state of basement water at that location, a “runaway” condition of cold seawater downhole flow into the crust was established, which persisted for more than 4 years. The existence of this condition, along with perturbations generated by it and by initial drilling operations observed at a properly sealed hole 2.4 km away, have been used with analytic and finite element model solutions to constrain formation permeability. The minimum threshold permeability allowing stable downhole flow is roughly 4 × 10−13 m2. A value of permeability similar to this (3–4 × 10−13 m2) is estimated on the basis of the elapsed time for initial perturbations to propagate between the sites (∼2.5 days). The amplitude of the long‐term flow perturbation observed at the sealed site (roughly 1.7 kPa) is smaller than that predicted by modeling (5–10 kPa). Models for flow in an anisotropically permeable layer show that this could be the consequence of low vertical permeability (e.g., arising from massive volcanic or sediment interlayering) or high permeability in the direction of the tectonic fabric generated at the ridge axis. Disagreement between the permeabilities estimated here with previous large‐scale estimates appropriate for the cross‐strike direction (the primary direction between the borehole sites) (10−10–10−9 m2) is difficult to reconcile; it is possible that the holes are poorly connected to zones of high permeability that facilitate the large lateral fluid and heat fluxes previously inferred at this young crustal site.

Crossing Hitler: The Man Who Put the Nazis on the Witness Stand

Hans Litten, a German-Jewish lawyer, ‘crossed’ Hitler in different ways, not only cross-examining him in one of the most famous trials of the Weimar Republic, but making him angry in the process—and paying the price once the Nazi leader was in power. Litten is relatively unknown in Germany today, even less so in the English-speaking world, and Benjamin Carter Hett's biography represents the first major English-language publication on Litten's life since the 1940s, when Litten's mother Irmgard published her account of her son's struggle. Hett's book is divided into three major parts, the first recounting Litten's youth in East Prussia and his subsequent transformation into a revolutionary socialist and celebrity lawyer in Berlin. The second part focuses on Litten's string of high-profile court cases and his arguably biggest moment, the cross-examination of Hitler in the infamous Eden Dance Palace trial in 1931, while the last part traces Litten's suffering under Nazi rule.

Coiled-Tubing Intervention Results in Substantial Savings

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 130682, ’High-Risk Coiled-Tubing Intervention Results in Substantial Savings,’ by F.N. Thom, SPE, and M.J. Taggart, SPE, BJ Services; J.D. Murdoch, SPE, Shell; and B. Ewing, Welltonic, originally prepared for the 2010 SPE/ICoTA Coiled Tubing and Well Intervention Conference and Exhibition, The Woodlands, Texas, 23-24 March. Problems with the tubing-retrievable subsurface safety valve (TRSSSV) and the subsea-tree valves resulted in a completion workover being scheduled. Before pulling the production tubing, the A-annulus was pressurized to 3,500 psi to reduce the differential pressure across the tubing. At 2,850 psi, there was a sudden loss in pressure, indicating a leak in the outer casing string. The workover was suspended and the well left in a safe condition. Planning for a full abandonment then was implemented. Introduction Teal P1 is a subsea well in the central North Sea. It was completed in July 1996 and had a peak production rate of 40,000 BOPD. During the completion stage, operational difficulties in setting the production packer in the wellbore resulted in several failed setting attempts. This resulted in a larger-than-expected volume of debris in the well. Because this debris had the potential to damage the turret seals in the floating production, storage, and offloading vessel into which the well produced, a debris-barrier assembly was designed and installed in a short time period. This debris-barrier assembly consisted of a preperforated tail pipe with a 3½-in. bridge plug installed in the base, all hung off with a packer in the 5½-in. production tubing at 945.5 ft measured depth (MD). In 2002, the TRSSSV failed to close during a routine test, and in 2005, the integrity of one of the subsea-tree valves could not be established because it failed a pressure test. A workover to replace the completion-tubing assembly was scheduled in an attempt to regain well integrity. Before pulling the completion tubing from the polished-bore receptacle (PBR) in the production packer, a caliper survey was conducted down to 972 ft MD, which showed a 1-in.-thick scale buildup in the completion. The wellbore then was bullheaded with 830-lbm/1,000 ft oil-based mud (OBM) to overcome the reservoir pressure, followed by approximately 23 bbl of seawater to occupy the top 1,000 ft of completion tubing. At this point, the completion tubing contained 830-lbm/1,000 ft (16-lbm/gal) mud, while the A-annulus contained 8.52-lbm/gal inhibited seawater equivalent to a hydrostatic differential pressure of 3,344 psi at the PBR at 10,195 ft MD. Because of the completion design consisting of two tubulars (one as the main production bore, and the other as a short tail pipe to access the A-annulus) a tubing-hanger-running orientation tool (THROT) was required to retrieve the tubing hanger. With an underbalanced fluid in the annulus and to provide adequate overbalance during unstabbing of the PBR, the drilling blowout preventers (BOPs) would need to remain closed, which could not be achieved with the THROT in place. Therefore, coiled tubing (CT) was rigged up to mill the scale deposits in the completion tubing down to 760 ft MD to permit access for a tubing cut in the 5½-in. tubing.

Enhancing Well Safety and Economics

Technology Update As the “low-hanging fruit” of the world’s oil and gas accumulations are more fully harvested, so the industry has been forced into tackling more complex and challenging projects such as ultradeep prospects, deepwater applications, and high-pressure/high-temperature (HPHT) wells to continue fulfilling the world’s appetite for fossil energy. This has led to more widespread use of nonconventional techniques such as drilling with casing, coiled-tubing drilling, underbalanced drilling (UBD), and managed-pressure drilling (MPD), including pressurized-mud-cap drilling (PMCD), with their attendant well-control and safety challenges. Among these challenges are Moderate to severe lost circulation Formation damage as a result of having to kill the well before tripping pipe Pore-pressure and fracture-gradient similarity, leading to kick/loss cycles and well-control problems Use of snubbing techniques to trip the pipe in and out of the hole above the “pipe-light” depth, with the associated added cost and risk. Overall operational safety Operational economics As a result, mitigating drilling hazards and reducing operational non-productive time (NPT) has become an extremely important facet of well operations. Downhole-Isolation-Valve System The need to address these challenges led to development of the Downhole Deployment Valve in the year 2000. This is an isolation-valve system consisting of a deep-set flapper valve that is run as an integral part of the intermediate casing string and set at a predetermined depth below the pipe-light depth, or deeper as operational requirements dictate, with a full-opening inside diameter equivalent to that of the casing. It is not a safety valve in the accepted sense of the word, in that it is not a fail-safe device, but rather is powered open and closed by the application of hydraulic pressure at the surface to one of two encapsulated control lines attached to the casing outside diameter (OD). The downhole isolation valve (DIV) can be run in two separate configurations, depending on operational requirements (Fig. 1).

Nine Lives: The Punitive Damage Class

The concept of the punitive damage class has a long and dubious lineage, extending back more than thirty years. During the 1980s and the 1990s the concept of the punitive damage class excited plaintiffs' attorneys, inspired countless academics, riveted at least a few defense counsel, and caught the attention of a scattering of federal judges. Nonetheless, certification of actual punitive damage classes has proved elusive, as court after court refused to give their imprimatur to the punitive damage class. In truth, the history of the punitive damage class has been one of repeated repudiation, punctuated by scattered, anomalous success (a point which its advocates have difficulty acknowledging). The punitive damage class's Waterloo, however, clearly arrived with the Supreme Court's decision in Ortiz v. Fibreboard Corp. ― celebrated, or at least commemorated in this symposium. Because the Rule 23(b)(1)(B) limited-fund class category has been the usual procedural vehicle for the punitive damage class, the Court's exacting requirements for certification of a limited-fund class action in Ortiz foredoomed almost every subsequent attempt to certify a punitive damage class. And yet the punitive damage class has proved enduring and hard to stave off. Hence, the Supreme Court's string of punitive damage cases, decided in the 1990s and into the twenty-first century, breathed new life into the moribund idea of the punitive damage class. The Court's suggestions of constitutional constraints on punitive damage awards provided a basis for advancing the argument for the Rule 23(b)(1)(B) limited fund. Seizing this jurisprudence, Judge Jack Weinstein cobbled together an innovative theory to undergird certification of a punitive damage class in In re Simon II Litigation, thus providing renewed hope to the advocates of the punitive damage class. Nevertheless, in 2005 ― more than twenty-five years after the first suggestion of a punitive damage class ― the Second Circuit unceremoniously buried the punitive damage class once again. For those who have lived through thirty years of mass-tort litigation, this renewed advocacy on behalf of the punitive damage class presents a rather intriguing, if not preposterous, prospect. The renewed arguments in favor of the punitive damage class take three forms. First, it is urged that courts take an expansive view of the Supreme Court's holdings in both Ortiz and Phillip Morris USA v. Williams, and interpret such decisions to support certification of punitive classes under Rule 23(b)(3). Second, other commentators suggest that the Supreme Court ought to grant review of a certified 23(b)(1)(B) punitive damage class, in order to create a specific exception to Ortiz that would authorize courts to certify punitive damage classes under 23(b)(1)(B). Third, plaintiffs' attorneys argue that CAFA opens the door to creative use of the punitive damage class through the law's authorization for “mass-action” cases. This Article examines these theories currently urged in support of the punitive damage class and assesses whether there actually is a viable means of sustaining a punitive damage class in the post-Ortiz, post-Simon II class action era. The Article concludes that prevailing class action jurisprudence, integrated with the Court's punitive damage jurisprudence, is unlikely to support certification of a Rule 23(b)(3) punitive damage class. In addition, the Supreme Court is extremely unlikely to create an Ortiz exception for punitive damage classes. Finally, the article suggests that CAFA cannot and does not support any Congressional intent to approve punitive damage classes as “mass actions” under this new jurisdictional statutory scheme.

Technology Focus: Well Control (January 2010)

Technology Focus It has been stated many times that all the easy wells have been drilled. It would stand to reason then that only problem wells remain. Even though this last statement is not entirely correct, our industry is facing increasingly costly incidences of pressure-related nonproductive time. Problems include narrow pore-/fracture-pressure windows, wellbore stability, depleted formations, formation damage, and excessive casing strings, among others. The industry has responded by developing managed-pressure-drilling (MPD) technologies. The goal of MPD is precise management of the pressure in the entire annulus. In most instances, a rotating control head is used, diverting the mud returns through an adjustable choke. This closed system allows precise imposition of surface backpressure on the annulus and enables precise measurement of the mud-return rate. The use a rotating control device and choke in this way is very similar to a constant-bottomhole-pressure method of well control. In September 2009, the SPE Drilling & Completions Applied Technology Workshop on Well Control was held in Rio de Janeiro, during which several companies involved in MPD made presentations on how their MPD technologies have enhanced well control. The closed system, which precisely measures surface pressures and mud-return rates, enables the detection of kicks (sometimes with less than 1 bbl of influx). Then, the mud-return rate is slowed to the prekick rate long enough to stop the influx and the well is killed, all without shutting in the well. In some cases, when a very small influx is detected, it is not even necessary to stop drilling. The papers selected to be highlighted in this issue all detail unconventional well-control methods that have been used recently. On the basis of these papers and presentations at the Applied Technology Workshop, it appears that well control with MPD will quickly become “conventional.” Well Control additional reading available at OnePetro: www.onepetro.org IPTC 11970 • “Killing a Gas Well: Successful Implementation of Innovative Approaches in a Middle-Eastern Carbonate Field—A Field Case” by S. Salehi, University of Calgary, et al. SPE 121045 • “Prevention of Vertical Gas Flow in a Collapsed Well Using Silicate/Polymer/Urea Method” by Istvan Lakatos, SPE, Reseach Institute of Applied Earth Sciences, University of Miskolc, and Geoengineering Research Group, Hungarian Academy of Science, Miskolc, Hungary, et al.