Technology Applications

Dennis Denney, JPT Technology Editor

Coiled-Tubing Drilling

BJ Services Co. announced that it provided coiled-tubing-drilling (CTD), engineering, and solids-control services for Well GA03 on Shell’s Gannet Alpha Platform in the North Sea. Following onshore trials in Aberdeen, the challenging sidetrack drilling operation began in February 2005. By April, the sidetrack was completed, and the equipment was rigged down and removed. The entire CTD operation from mobilization to demobilization was completed in 81.5 days. A specially built CTD injector-support frame supported the hydraulic injector because the drilling blocks had been removed from the derrick. In addition to the CT equipment, the company supplied Zone 2 ancillary equipment to support the operation fully, including mud pumps, a package to handle drilling fluids, a data-acquisition system, a well-control package, a solids-control unit with additional mud tanks, and a new mud/gas separator. Fig. 1 shows the CTD equipment installed on the Gannet Alpha Platform pipe deck during the operation. The CTD reel is on the right, with the CTD cabin behind it. The CT workstring reel is to the left. The drilling reel and work string are mounted on the track-and-trolley system to move them without using a platform crane.

Fig. 1—BJ Services Co. CTD equipment for Well GA03 on Shell’s Gannet Alpha Platform in the North Sea. The drilling reel is on the right, and the work-string reel is on the left.

Fig. 1—BJ Services Co. CTD equipment for Well GA03 on Shell’s Gannet Alpha Platform in the North Sea. The drilling reel is on the right, and the work-string reel is on the left.

For additional information, visit www.bjservices.com.

Polymer-Free Fluid Boosts Production

The reliability of gravel packing, or frac packing, in high-pressure/high-temperature (HP/HT) environments can be improved by use of Schlumberger’s nondamaging, solids- and polymer-free ClearPAC HD fluid system. This water-based gravel-carrying system is composed of a viscoelastic surfactant (VES) and brines that can be mixed in densities up to 14 lbm/gal for controlling high downhole pressures (Fig. 2). It is stable in downhole temperatures up to 300°F and can be used in either circulating or squeeze modes. When used to pack long, HP/HT horizontal well intervals in conjunction with the Alternate Path technique, licensed from ExxonMobil, it is a particularly effective well-control agent. This fluid can be prepared simply by adding a VES gelling agent to one of two brines: calcium chloride or a combination of calcium chloride and calcium bromide. Full viscosity develops rapidly without degradation once the surfactant is completely dispersed in the brine, saving significant preparation time compared with that needed for crosslinked polymer-based fluids. The resulting fluid displays low friction and excellent carrying properties. The compatibility of the fluid with some enzyme and chelating agents allows simultaneous gravel packing and filter-cake cleanup in open holes at temperatures lower than 180°F. In addition to synthetic- or water-based muds, it tolerates most oil-based-fluid contamination for packing wells drilled with oil-based muds. Viscosity breakdown occurs upon initiation of crude production, resulting in high retained permeabilities in the gravel pack.

Fig. 2—Suitable for temperatures up to 300°F and densities up to 14 lbm/gal, Schlumberger’s ClearPAC HD gravel-carrying system can be blended with a variety of brines to handle the wide range of temperature and density domains shown

For additional information, visit www.slb.com/clearpac_hd.

Sucker-Rod-Pump Controller

R&M Energy Systems has introduced its Guardian Sucker-Rod-Pump Controller (Fig. 3), a digital solution for production control. The system can control all forms of reciprocating artificial-lift systems. The controller increases production and improves energy efficiency by integrating motor control, speed optimization, logic, pump-fill control, and rod-load control into one unit. At any instant during the life of a well or within a pump cycle, there is a single constraint that limits production. This controller forces the system to operate at the particular constraint at each instant of time, thus maximizing production. Multiple-constraint optimization is particularly beneficial in applications with variable inflow conditions, such as in coalbed-methane, high gas/oil ratio, and thermally stimulated wells. The controller determines polished-rod and downhole-pump positions, velocity, and load without requiring external rod-position or load sensors. These sensorless-system variables are observed through monitor displays or recorded as time-based graphs for later use and review.

Fig. 3—R&M Energy Systems’ Guardian Sucker-Rod-Pump Controller

Fig. 3—R&M Energy Systems’ Guardian Sucker-Rod-Pump Controller.

For additional information, e-mail info@rmenergy.com.

Advancement Cuts Drilling Time

ExxonMobil announced development of an optimization process that consistently reduces the drilling time required for oil and gas wells by up to 35%. Their Fast Drill Process achieves this performance with real-time computer analysis of the drilling system’s energy consumption. This analysis, in turn, helps improve management of factors that determine the drilling rate, such as weight on the drill bit, rotary speed, and torque. The company has used the process in many of its operating areas, and it improves performance in a broad range of conditions, including hard and soft rock, deep and shallow wells, and high- and low-angle wells, in a variety of mud weights. It has shown comparable success in exploration, delineation, and production wells. The process quantifies the hidden cost of slow drilling. Historically, drilling rates have been evaluated by comparing performance to other wells in the same area. However, there has been no method to confirm that the comparison well was, itself, a high-performing well. This process allows the operator to make design changes to achieve the objective theoretical performance in a given well. Much of the performance improvement achieved has come from this ability to objectively justify design changes needed to extend previous performance limits.

For additional information, e-mail fred.e.dupriest@exxonmobil.com.

Geopressure-Data Management

A new software system for managing geopressure information was introduced by Knowledge Systems. The Pressworks system is a relational database developed to help operators protect, share, and store pressure-related data from diverse sets of well and reservoir information and well-log data. It enhances a suite of software products, which includes the Drillworks system, an integrated family of software applications for geopressure and geomechanics analysis. In addition to serving as a corporate store for an operator’s pressure-related data, the new relational database also can connect to industry-standard databases, proprietary data stores, and commercial data vendors by use of the Internet. Job-specific information is uploaded back to the database to help streamline the project and provide quality control for information accessed by other users. Users on other systems can browse and select pressure data and conduct queries through the software’s browser-type interface, Scout. Operators currently using the company’s system for geopressure and geomechanical analysis can improve integration of regional data and analyses, enhance and streamline existing workflow for the lifespan of a project, increase corporate security for valuable data and analysis, and enhance other users’ access and use of the analysis through the browser interface.

For additional information, visit www.knowsys.com.

Prototype Testing Validates CNG Transport System

EnerSea Transport LLC, a compressed-natural-gas (CNG) marine transport and storage company, has completed its 2-year, comprehensive, prototype-testing program confirming the functionality, operability, and safety of its proprietary Votrans CNG marine-transport system (Fig. 4). As worldwide demand for natural gas grows, the CNG transport system provides an option for transporting gas in many applications. A small-scale system was purpose-built to perform loading and unloading cycles at planned operating pressures and temperatures, as well as in upset and abnormal operating conditions. The multicylinder test facility incorporated all process equipment required to simulate functionality of the complete system and was operated to confirm the effects of switching banks of cylinders and dynamically cascading gas and liquid through the system. Automation, control logic, and valve systems were developed for full-scale projects. Testing was completed on the CNG cargo tanks, which included the manufacture of 10 full-scale CNG cylinders. Fatigue and burst testing of these cylinders was conducted in a specially constructed low-temperature test facility. The American Bureau of Shipping, a classification society, provided the overall testing and guidance during the planning and engineering phases. Classification-society approval provides further validation to industry and regulatory authorities worldwide that the system functions in a safe and operationally reliable manner, thus supporting the commercial viability of this transport system.

Fig. 4—EnerSea Transport LLC’s Votrans CNG marine-transport system.

Fig. 4—EnerSea Transport LLC’s Votrans CNG marine-transport system.

For additional information, visit www.enersea.com.