Low viscosity ester fluid designed for deepwater conditions
A low viscosity ester-based fluid with the addition of two new rheological control agents developed by Halliburton Energy Services recently completed successful jobs for an operator in the Gulf of Mexico. The fluid is an alternative to synthetic-based fluids. The fluid, known as PetrofreeTMLV, is claimed to provide operators with the ability to use ester-based fluids in deepwater conditions. The fluid is claimed to offer materials with lower environmental impacts, without compromising technical capabilities.Also, in order to combat the lower and higher temperature ranges typically seen in deepwater situations, Baroid Drilling Fluids formulated two new thinners, ColdtrolTM and ATCTM, to work in conjunction with the ester-based fluids. The former additive is said to thin in the 40°F and lower temperature ranges of deepwater without adversely affecting the higher temperature rheology. The ATC additive helps reduce rheologies in all temperature environments quickly.Both are useful when lowering the yield point and gel strengths before running casing, and maintaining properties during the drilling phase as well. The ester base fluid takes advantage of a sustainable source for one of its components - renewable palm or coconut oil.
65th expandable liner system installation
A record installation was achieved by the Completion Systems Division of Weatherford Intenrational with the group's Alternative Borehole Liner (ABL) in a 44-degree deviated hole. The hold was being drilled on the Fahud-335 well for Petroleum Development Oman in Oman. A total of 29 meters of liner was installed at a total depth of 712 meters (covering a 20-meter shale interval) and at an angle of 44 degrees, 267 meters below the 9 5/8-in. casing shoe.
The previous installation record was 56 meters below the casing shoe. After installing the liner in a 12-1/4 in. under-reamed section, the remaining 380 meters of the 8-1/2 in. hole was drilled to 1,092 meters total depth and the 7-in. liner was run through and cemented successfully.
This system allows the selective isolation of problem sections in a wellbore without loss of hole size. Unlike conventional casing and liner, the ABL isolates the specific problem area, rather than the entire section back to the previous casing shoe.
Emulsion-based soap reduces costs, rig time
An emulsion-based casing cleaning soap known as "oil-based soap" (OBS) was successfully applied on more than 20 casing cleaning operations off Norway, primarily on the Statfjord and Sleipner fields operated by Statoil. The soap was developed by BJ Services.
This casing cleaning system reduces rigtime, is environmentally safe, and replaces a more expensive method. The conventional method consists of pumping base oil, followed by a sequence involving two or three cycles with water-based viscosified soap pills, followed again by pumping seawater.
The new method is based on pumping only a small volume of base oil, followed by pumping a soap containing a specific water volume, which is emulsified into a larger base oil pill. Thereafter, a water-based wash fluid primarily for water wetting purposes is pumped, followed by seawater.
During the initial applications carried out on the first two wells, the casing cleaning pill composition and volumes were optimized using a laboratory evaluation with a VG-viscometer prior to the operation. During a casing cleaning operation on Statfjord A-07A, the oil-based mud (OBM) was first displaced by 5m3 base oil, followed by a 30m3 emulsion pill. This emulsion pill consisted of 65% base oil. The remaining 35% was a mixture of water and casing cleaning chemicals. Following the emulsion pill, a 10m3 low viscosity wash fluid pill was pumped. Finally, seawater was pumped until sufficient cleanliness was observed, whereupon the well was displaced to completion fluid. After pumping one hole volume with seawater, the effluent water exhibited a steady cleanliness of 96 NTU, and pumping of seawater was terminated. When the washing pipe was pulled out of the hole, it was completely clean.
In light of the wash pipe tool configuration, optimum pumping rate, wash pipe rotation and reciprocation were not practical. The BJ Services-Statoil experience on the initial Statfjord and Sleipner wells indicated that when a drilling operation is followed directly by a casing cleaning operation without delay, pumping of an efficient cleaning pill is usually sufficient to clean the well without rotating and reciprocating the wash pipe.
By carrying out the pumping sequence using OBS, significantly less fluid volume is required, as compared with the traditional casing cleaning approach. Because the OBS pill is sufficiently unstable, it is possible to separate most of the base oil from the effluent fluid, following a casing cleaning operation. This means that the base oil may be recycled for use in future drilling, and casing and cleaning operations. Therefore, waste production and related waste handling costs are also dramatically reduced. An added plus is that because the OBS cleaning process is completely contained, no discharges are made into the sea.
In field and laboratory tests, the new OBS method has proven to be far superior to the traditional casing cleaning method. Casing cleaning operations carried out by Statoil have shown a significant reduction in chemical consumption and rig time, representing a 30-50% reduction.
Satcom network links Africa well sites with operating centers
A high-speed satellite communications network has been extended into Africa, making up a network similar to that existing in the Gulf of Mexico. Through the use of portable remote units, the HalLinktrademark network is now operational for Halliburton Energy Services product service lines in Angola, Nigeria, and Algeria. The Africa units joined the network already operational in the United States, Canada, Mexico, Colombia, Venezuela, Bolivia, Peru, and Argentina, with more strategic locations scheduled as the mobile satellite network continues to expand. The network enables a reliable, cost-effective means of communications at remote offices and well sites.
In Angola, the network has units mounted on two stimulation vessels -Falcon Tide and War Admiral. Several stabilized, skid-mounted, quick-deploy communications units are also available for use on semisubmersible rigs and/or other floating structures offshore West Africa, just as they are in the Gulf of Mexico. The satcom units provide links with accommodation units in Mexico, and with other working vessels in Lake Maracaibo (Venuzuela).
The network is a component of the firm's Real Time Reservoir Solutions(tm) (RTRS) strategy. Data can be transmitted to operations centers, visualization rooms, asset members, or users offices via the Internet at any location. Individuals can collaborate, share knowledge, and solve problems from any point on the globe.
The network creates a link from well sites to strategic operational bases. The link combines fixed sites in Africa with the existing mobile network.
Onshore and offshore operations are available in the U.S. operational area of the Gulf of Mexico through stabilized systems, which are installed on three stimulation vessels -Stim Star I, Stim Star II and the Gulf Stim - and in the Mexico operational area on the stimulation vessel Cape Hawke, which is also fitted with a stabilized system. Also in the Gulf of Mexico, several communications units are available for use on semi rigs and/or other floating structures. Partnering with Kellogg Brown & Root business unit has provided satellite communications for its Mexico accommodations units, the Safe Caldedonia and the Semac in the Gulf of Mexico. In Venezuela on Lake Maracaibo, several operations barges are also fitted with stabilized communications systems. All of these units were brought into service in late 1999 and 2000 as part of the global rollout of the company's RTRS strategy.
