In 2011, the Kuwait Oil Company (KOC) considered enhancement of equipment specifications for deep drilling rigs to integrate state-of-the-art technologies. UPDC Rig 776 was the first to be upgraded, and this work was handled as an integrated project by the rig contractor working closely with the field operator. With regard to the rig design, major changes were made to enhance safety, capacity, and automation of the drilling functions.
Purpose of the Upgrade
The drilling of future deep high-pressure/high-temperature wells in Kuwait will become more challenging. New frontier areas with increased depth and formation difficulty are being targeted. To ensure that the deep drilling rigs will be able to meet these future challenges and to improve safety and operational performance, KOC has enhanced the deep-drilling-equipment specifications for their new contracts.
For Rig 776, this required a major upgrade or replacement of all core rig components.
- The subbase height had to be increased to be able to incorporate a full 15,000-psi blowout-preventer (BOP) stack rig-up.
- The topdrive system had to be upgraded to cope with higher mud-flow rates and pressures, and a control system for the driller was to be installed.
- Mud pumps were replaced with new 2,200-hp pumps, producing up to 7,500 psi.
- The rig power system was upgraded with five new 1,855‑bhp (maximum) engines and a new selective catalytic reduction (SCR) system.
- An upgrade of the drawworks included an integrated disk brake system and installation of a semiautomated control system for the driller.
- The iron roughneck was enhanced.
- The mud system was upgraded.
These improvements were aimed at enhancing safety, capacity, and automation of the drilling functions. In addition to these major changes, the rig camp was completely refurbished and the camp power generation was upgraded to silent packages.
Rig-Upgrade Works
Once Rig 776 finished drilling the last well before the upgrade, the rig was prepared for the yard work. As the rig commenced to rig down for the move to the project yard, all equipment had to be cleaned properly. The mud tanks had to undergo sand blasting before inspections could be conducted. The cleaned equipment was then moved to the project yard. The rig offices were set up in the project yard to provide extra office space.
Subbase and Mast. The subbase height had to be increased by 10 ft. This was accomplished by changing out all existing subbase legs. With the new subbase height, all stairs, escape slides, piping and hoses, and the personnel elevator to the rig floor had to be modified or replaced and the V-door ramp had to be extended.
In addition to increasing the height of the subbase, the entire subbase and mast underwent inspection and recertification. This required sand blasting of all components, inspection, and repainting. Any defects found had to be repaired, with parts replaced as needed.
Once work on the subbase and mast was completed, a new 120-ton BOP hoist system had to be installed. The spill containment (drip pan) was replaced under the rig-floor area.
On the rig floor, the existing ST-80 iron roughneck had to be replaced with a large-capacity IR10-100 roughneck. A new 20,000-lbm air tugger also was installed.
Drillers Cabin. The old driller’s console was to be replaced with a modern enclosed driller’s cabin that holds joystick controls for the drawworks. This cabin incorporates touch-screen controls for all major rig functions (Fig. 1).
Topdrive. The topdrive was stripped down, and all parts were inspected. The main shaft had to be upgraded from 3 in. to a new large-bore 4-in. shaft with a 7,500-psi pressure rating.
Drawworks. The existing drawworks had to be completely stripped down and inspected and overhauled. The old drum shaft and drum had to be replaced. A new disk braking system was installed. New semiautomated controls were installed for the driller.
Mud Pumps and Discharge Piping. The three original 1,700-hp mud pumps were replaced with new 2,200-hp pumps with 7,500-psi output. These new pumps include a quick liner and piston change system. Also, an independent charge-pump skid was added to the system. These new pumps can deliver more mud volume at higher pressures, as required for the new drilling program.
All old 5,000-psi mud-discharge lines, mud-discharge manifold, stand-pipe manifold/lines, and rotary hoses had to be changed to larger-inner-diameter and higher-rated 7,500-psi lines.
Mud System. The existing mud tanks were cleaned, sand blasted, inspected, and repaired as required. The mud-volume capacity was increased to 4,500 bbl with the incorporation of additional tanks. New larger 20-hp agitators were installed to improve agitation of the heavy muds (up to 20.5 lbm/gal) used in Kuwait. Also, one new shale-shaker unit was installed to provide better solids removal.
Rig Engines, SCR System, Accumulator Unit. To cope with the higher power demands of the new mud pumps and mud system, the five existing 12-cylinder engines were replaced with larger, 16-cylinder engine packs. The old SCR system was replaced with a new SCR system that integrates automated engine control in the driller’s cabin.
The original nine-station accumulator was replaced with an upgraded 12-station unit.
Camp Refurbishment. The entire main camp and rigsite camp underwent refurbishment in the project yard. One by one, the cabins were cleaned and repaired and refurbished, as required. Several cabins were replaced with new-built cabins.
24-Hour Testing and Final Inspection. Once all work was completed, the rig entered into a 24-hour maximum-load test, which was witnessed by KOC representatives and a rig-inspection contractor. The test was set up to simulate heavy drilling conditions. To draw maximum power from the engines, all three mud pumps were pumping, the topdrive was running, and all agitators and shale shakers were running. The rig systems had to withstand this 24-hour load test without any shutdown of more than 30 minutes.
The rig was then rigged down and moved to the first location in the South Burgan field (Fig. 2 above). During rig-up, the remaining smaller outstanding jobs were completed and a final prespud check was conducted by KOC. Once all was accepted, the rig spudded the first well on 18 January 2012.
Main Challenges and Recommendations
Yard Operations and Multiple Projects. Many challenges of this project stemmed from the fact that, concurrently, there was a second upgrade project (Rig 3) and two new rigs being built. To deal with this, three project managers with their teams were used (one for the new builds and one each for the upgrades). The upgrade teams for Rig 776 and Rig 3 worked at the yard in Kuwait, while the new rigs were built in Dubai.
Rig 776 was the first rig to undergo the upgrade works, followed by Rig 3. The rigs were expected in the yard in Kuwait within a month of one another, so the available yard space had to be used efficiently. The project yard was separated into two areas to keep equipment and materials from getting mixed during the project.
Materials and Logistics. Another substantial challenge was the coordination of all purchasing activity. Large quantities of equipment and parts were ordered for all four projects. This required the use of dedicated warehouse and logistics teams to process the ordering, tracking, and shipping of materials. A major problem was slippage in promised delivery times from various vendors, some of which resulted in delays to the project work. To overcome these problems, some equipment had to be urgently air-freighted and some had to be shared or borrowed from other rigs until the new equipment arrived in Kuwait. The main lesson from this is that the sooner the equipment is ordered, the better.
Refurbishing Existing Equipment. While planning for the upgrade, all efforts were made to establish the condition of existing equipment accurately and to anticipate what work and which parts were required. But some of the equipment conditions remained unknown until the particular item was completely dismantled in the yard. On a few items, equipment conditions were found that were worse than expected, and replacement parts had to be ordered on an urgent basis.
For future upgrade projects, it is recommended to negotiate with the parts vendors to provide all possible required critical parts ahead of time and then return the parts that are not needed. This will avoid waiting-for-parts project delays.
Connecting Systems From Different Vendors. The new driller’s cabin and controls and the SCR house were made by one manufacturer, and the main rig equipment was supplied by other vendors (drawworks, topdrive, mud pumps, and main engines). Getting the equipment set up properly to ensure smooth communications between these systems was vital and had to be done with care, using service technicians from all involved manufacturers.
Initial Results. After final testing and commission of the upgrade, the first deep exploratory well was drilled with the modified rig in the Kuwait South Burgan field. While drilling the first well, no major problems were experienced with the newly installed instrumentation system or other upgraded equipment. The initial well was drilled under planned time, with no lost-time injuries or environmental incidents.
This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 164019, “Re-Engineering and Upgrade of Semiautomated 3,000-hp Drilling Rig for KOC HP/HT Exploration Program in Frontier Areas—Case History of UPDC Rig 776,” by A. Al-Saleh, SPE, M.D. Al-Khaldy, SPE, A.A. Shehab, SPE, F.A. Al-Naqa, SPE, and S. Baijal, Kuwait Oil Company; M.F. Karam and S. Schmidt, United Precision Drilling; and D.C. McKinnell, SPE, Total Kuwait, prepared for the 2013 SPE Middle East Unconventional Gas Conference and Exhibition, Muscat, Oman, 28–30 January. The paper has not been peer reviewed.