John Waggoner • Houston
VAALCO drilling off to strong start in Gabon
VAALCO Energy has drilled one pilot hole south of the original Ebouri discovery and a second pilot hole northeast of the original discovery offshore Gabon. The holes delineated additional Gamba sandstone reservoir above the oil/water contact, thereby increasing the acreage and reserves of the Ebouri field. VAALCO is completing the development well horizontally on the same orientation as the second pilot hole. First oil production from the well was expected (at presstime), the company says.
The company also hit with the North Ebouri appraisal well in the Etame block northeast of the Ebouri platform. The well struck a 21-ft (6.4-m) oil column, further expanding Ebouri field. VAALCO plans a sidetrack to optimize the location for a possible second horizontal development well. In addition, the company plans two exploration wells (North Etame and South East Etame) on newly mapped structures. The wells will be drilled back-to-back usingPride Cabinda.
VAALCO expects to bring total production from the Etame license to approximately 25,000 b/d of oil. The Etame license areas currently produce approximately 20,000 b/d, of which VAALCO has a 28.1% working interest.
The piling operations were performed on schedule and without incident exactly as planned, despite the soil variety. The $2-million drilling and grouting contract was the first ever for newly formed Large Diameter Drilling (LDD) Ltd.
Since the project is based on a floating construction vessel, heave forces were the main concern. The motion of the vessel could damage the well or the equipment, causing project delays.
Given the mere 1.5-in. (3.8-cm) radial tolerance from the bit through the center of the 42-in. (107-cm) tubular pile, LDD opted to use a passive heave compensator to keep the drill from snagging on withdrawal or from touching the base of the pile.
The heave compensator, with a 3-m (10-ft) stroke for safe working loads up to 60 tons (54 metric tons), was able to reduce point loading to just under a ton (907 kg).
“As far as we are aware, no one else has ever used a lift compensator such as this for a drilling and piling operation,” says Andy Seager, operations manager at LDD.
Soil conditions posed an unexpected twist when high concentrations of clay were encountered. Two years previously VAALCO installed the Avouma platform, and given the similar geology, opted to forego additional site investigation.
Once drilling began, clay appeared. At times it was unconsolidated and inter-banded with weak layers of mudstone, siltstone, and sandstone. Since the hard mudstone and sandstone sub-base of the formation ruled out a driven pile solution, the choice of raked piles tended to aggravate the problem.
Once the socket was completed and before the drill bit and bottomhole assembly were removed, the hole was backfilled with a proprietary shaft-stabilization mud to support the unconsolidated clays and weak layers. This increased the socket stand-up time for safe pile insertion and grouting.
AnTech wellhead outlet stays cool in HP/HT wells
AnTech has re-engineered its wellhead outlet to operate safely in the higher temperatures generated by high-pressure/high-temperature wells. The outlet responds to customer demand for an ATEX-certified tool that could be operated safely in today’s hotter wells, the company says.
“With the dramatic rise in the number of HP/HT wells, it was time to take the tool to the next level,” says Toni Miszewski, MD of AnTech.
AnTech’s wellhead outlet is ATEX-certified for a number of applications.
Previously, AnTech’s wellhead outlet was rated at a maximum Ta (ambient temperature) of 40° C (104° F), which indicates the maximum external temperature around the component; not the air temperature, with a maximum current of 26A. With these specifications, AnTech was able to offer the highest safety rating possible: T6, as the temperature of the device would never rise above 85° C (185° F), even if the outlet was operating at maximum Ta and current levels.
AnTech plans to further develop its range of wellhead outlets. In 1Q 2009, the company expects to apply for certification of a wellhead outlet that will perform safely at a maximum temperature of 125° C (257° F).
Halliburton bridge plug designed for unsupported casing
Halliburton has unveiled the Evo-Trieve bridge plug, a retrievable monobore plugging device that does not require a predetermined setting restriction for locating or sealing within the production completion.
The new product is V0-qualified per ISO 14310 to 7,500 psi (0.14 mPa) at 275° F (135° C) and its design includes large slip and element footprints to provide pressure-holding capability in unsupported casing. Debris tolerance has been verified through a comprehensive flow loop testing program, the company says.
The device can be deployed using conventional slickline with the DPU downhole power unit and can be retrieved with industry-standard GS pulling tools.
BJ Services soups up Seahawk deepwater cementing units
In order to meet operators’ demands for reduced mixing and pumping times during deepwater cementing, BJ Services continues to develop higher horsepower cementing units with more configuration options.
In recent months a 1,600-bhp version and a 2,300-bhp model were developed to handle displacement tasks at higher rates and pressures. High-speed fiber optics let the equipment communicate remotely.
Twin-mixing capabilities are being developed for the 2,300-bhp Seahawk unit for blending rates to 20 bbl/min to be deployed on an ultra deepwater drillship in the Gulf of Mexico in 2009.
ExxonMobil hits on Brazilian presalt well
ExxonMobil has found hydrocarbons in Brazilian presalt formations near other major finds in the offshore Santos basin.
The company reported Azulao-1 hit pay in the Azulao field of the BM-S-22 block in Santos on Jan. 16, 2009. ExxonMobil was not required to report estimates of potential recovery, but plans to continue drilling to target depth.
Oil found in this area of Brazilian presalt formations can be at water depths of more than 2,000 m (6,562 ft) and 5,000 m (16,404 ft) below the seabed, making production both challenging and expensive.
This Azulao field is located close to the Tupi and Carioca fields, both operated by the Brazilian national oil company Petrobras.
Work is under way to pin down estimates, but Petrobras has previously stated that the presalt reserves from Tupi could range from 5-8 Bboe.
The rigWest Polaris drilled the hole.