14 JULY 2005

Calcium Control in Drilling Fluids—PQCorp. has introduced its Valfor 100 as ameans to control unwanted calcium inwater-based drilling fluids. This molecularsieve (Fig. 1) is specifically engineered forthe removal of Ca2+. The “cage-like” frame-work makes it more effective than sodiumcarbonate in both the amount of calciumremoved and the time of reaction. It alsocan be used, to a lesser extent, for removingmanganese and iron. The principal use hasbeen as an additive to silicate-based drillingfluids. Before drilling calcium-based forma-tions such as anhydrite, the system is addedto the drilling fluid. Laboratory resultsshow that 0.25 wt% of the system canreduce calcium-induced silicate depletionby as much as 20%. Field results in westernCanada confirmed the slower depletion rateas well as better maintenance of drilling-fluid properties such as fluid loss and rheol-ogy. The system is a crystalline aluminosili-cate and is, therefore, completely inorganic,nontoxic, and noncombustible.

For additional information, e-mailMike.McDonald@silicates.com.

Riserless Subsea-Well Intervention—Saipem America Inc. (Sonsub) has devel-oped its Riserless Modular Subsea WellIntervention system for workovers of sub-sea wells. In an emergency situation, thesystem disconnects the surface-deployedumbilical from the subsea equipment, leav-ing the lubricator and blowout preventer(BOP) safely attached to the well, eliminat-ing the need to keep surface winchesattached to the subsea equipment. The sys-tem modules include a lubricator, BOP, run-

ning tool, and an umbilical with a fail-safedisconnect. The BOP and running tool areconnected together on the surface andinstalled with guidance from a remotelyoperated vehicle (ROV). The lubricatormodule (Fig. 2)—including a tapered stressjoint for control of bending loads applied tothe BOP, a disconnect module, and a greasehead for insertion of the workover tool—isassembled on deck and installed with ROVguidance. The umbilical is then lowered todepth and connected to the BOP module byan ROV. The umbilical connector is fail-safein that it is hydraulically powered to con-nect and remains connected until hydrauli-cally powered to release. Normal operationof the connector is controlled through theumbilical; however, a secondary releasesystem, powered by an ROV, is provided asa contingency. The multiple hose passagesof the umbilical are sealed by check valvesthat are opened as the connector is pow-ered to the connect condition and auto-matically closed as the connector is pow-ered to release. The connection or discon-nection is accomplished with a singlehydraulic cylinder. The system is for use toa depth of 7,000 ft using the company’spatented concentric-pipe Subsea Produc-tion Riser. For wireline service, the BOP israted at 10,000 psi and is suitable for H2Sand CO2 service. The BOP is equippedwith three sets of rams, two in the produc-tion bore and one in the annulus, and it hasa bypass loop for each bore to equalize thepressure across the rams after they havebeen closed.

For additional information, e-mailtracie.ross@saipemamerica.com.

Heavy-Oil Viscosity Reducer—Proflux is anew production technology from OilFlowSolutions Ltd. that is designed for heavy andwaxy oils. It is a cost-effective productionmethod used to increase production by lib-erating stranded high-viscosity reserves. Itacts on heavy oil by reducing the viscosityup to several orders of magnitude, allowingit to flow through conventional comple-tions, in field-transport lines, process cen-ters, and main oil pipelines. Similarly, waxyoil can flow and be transported at tempera-tures well below its native pour point. Theproduct is based on a dispersion technologythat creates an encapsulated oil/water con-tinuous phase, delivering flowing viscositiesof 20 to 100 cp at ambient temperatures foroils having an original viscosity of up to70,000 cp. Unlike emulsion-based process-es, the dispersion can be separated easily tore-establish the original or enhanced oilproperties at the point of delivery or sale.The separated product can be recycled andreused multiple times.

For additional information, e-mailmcrabtree@agtenergy.com.

Metal-Sealed Bits—Hughes Christensenhas introduced its MXL long-life motor bits:high-speed Tricone bits designed fordemanding applications (Fig. 3). The designhas a new cutting structure, configurablehydraulics, and a highly reliable bearing.This bit series uses a single energized metal-seal bearing package. All relative rotarymotion takes place between two lubricatedmetal-seal surfaces. A wider metal-seal sur-face increases sealing capacity by up to 20%.The proprietary wear-resistant surface

Technology ApplicationsDennis Denney, JPT Technology Editor

Fig. 1—PQ Corp. Valfor 100 molecu-lar sieve.

Fig. 2—Deploying the Sonsub lubri-cator module.

Fig. 3—MXL long-life motor bit fromHughes Christensen.

16 JULY 2005

retards seal wear with its lower coefficient offriction. The backup ring uses a stress-engi-neered shape that extends its operating lifeand improves its ability to keep out debris.The redesigned energizer-seal geometryimproves sealing efficiency to apply the opti-mum face load to seal surfaces under all con-ditions. The redesigned bit uses optimizedcompact-carbide grades, re-engineered toothshapes, and strategically placed cone savers.The cone savers protect the cone steelagainst abrasion by cuttings. The bits use abiased or unbiased hydraulic configurationdesigned for the specific application.

For additional information, visitwww.HCCbits.com.

Deepwater Well-Control System—Oper-ator interest continues to rise in equipmentthat can control subsea wells. Well controlis especially important in the fast-growingdeepwater sector in which costs tend toincrease in proportion to water depths. TheExpro Group’s high-pressure 15,000-psilanding string and its associated controlsystem are fully adaptable to 3-, 5-, or 7-in.-bore landing strings and provide hydraulicand electrical control and monitoring ofsubsea valves and completion equipment(Fig. 4). Compatible with all horizontalsubsea wellheads, the systems are qualifiedfor use in water depths to 10,000 ft. Thesystems can be deployed in applicationswith differential pressures of up to15,000 psi and temperatures of up to 300°F.

The control systems have a modular, flexi-ble design to adapt to a wide range of oper-ator applications and subsea test-tree con-figurations. They also achieve rapidresponse times that meet and exceed theindustry emergency-disconnect require-ments for well closure and disconnect inless than 15 seconds. The system containsthree valves. The lubricator valve enableslong intervention tool strings to be madeup or recovered from the live well. Theretainer valve closes before unlatching thesubsea landing string from the wellhead,preventing any hydrocarbons in the land-ing string from escaping into the environ-ment (marine riser or onto the drill floor).The subsea test tree allows safe operationson a live well during well test or comple-tion operations. Dual ball valves provideprimary well-control barriers. A latch with-in the assembly provides the means to dis-connect and reconnect the landing string,leaving the closed-in valve section in place.

For additional information, visitwww.exprogroup.com.

Cementing in High-Stress/High-Tem-perature Regions—Schlumberger hasincreased both the temperature and flexi-bility range for permanent zonal isolationof hydrocarbon reservoirs with itsFlexSTONE HT cement system. Thecement mechanical properties can be main-tained throughout the entire working life ofa well at temperatures ranging from 40 to

482°F, which can be encountered whiledrilling for and producing deep gas reser-voirs that often are highly pressured. Pre-job modeling determines the set-cementmechanical properties required for the spe-cific formation rock properties and pres-sure/temperature changes that likely will beencountered. This approach considers stat-ic downhole parameters and the downholechanges that can occur during pressuretesting, stimulation or fracturing treat-ments, drawdown tests, or formation load-ing. An improper cement system can leadto mechanical damage of the cement sheathbehind casing or the creation of microan-nuli, both of which can compromise a well’shydraulic isolation. This cement systemuses flexible and expansive materials, andthe slurries can be mixed to have a very lowYoung’s modulus (435,000 psi), whichenables the cement sheath to conform tothe tensile and compressional stressesimposed on it during thermal or mechani-cal expansion (Fig. 5). An optimized parti-cle-size distribution allows increasing thesolids content of the slurry and reducingthe water content. Densities for the cementsystems range from 10 to 21 lbm/gal. Also,with up to 2% linear expansion capability, itis possible to prestress this cement,enabling the sheath to close a microannulusof several hundred microns in size, poten-tially sealing fluid-leak paths.

For additional information, e-mail cementinfo@slb.com.

Fig. 5—Comparison of two Schlumberger FlexSTONE HT cement sys-tems with a comparative Class-G-plus-silica cement system, show-ing how mechanical properties of the FlexSTONE HT systems can becontrolled.

Fig. 4—Expro Group’s deepwater well-con-trol system.

Technology Applications

JPT