The Endeavour well drilling project is located 60 miles offshore the east coast of Trinidad. It is one of the largest gas fields, with a significant gas reserve that will meet the energy needs of Trinidad and Tobago.
The Endeavour well is the third in a three-well programme drilled on block 5(c), which is approximately 80,000 acres in size. The other two wells are Victory and Bounty, which were discovered on 14 January and 13 August 2008, respectively. The three wells have estimated recoverable reserves of over four trillion cubic feet of natural gas.
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The three wells were selected from the interpretation of a 760km2 3D seismic data set covering the block and offsetting producing fields. The project is being developed by BG Group and Voyager Energy. BG Group is the operator of block 5(c) with a 75% working interest. Voyager Energy holds the remaining 25%.
All drilling operations on the Endeavour well were completed in 2009. The prospect was declared commercial in July 2011. An appraisal drilling programme will be conducted at the field in 2013, subject to the approval of the project partners.
Endeavour project background
Trinidad is a basin with great potential, with multiple and large exploration and development opportunities. Natural gas from the country supplies the world’s largest natural gas markets and provides about 80% of the US’s liquefied natural gas (LNG) requirements.
In 2004, Challenger Energy entered a participation agreement with Canadian Superior Energy to explore for oil and gas on the Mayaro/Guayaguayare Bay block with the Petroleum Company of Trinidad and Tobago. The block was awarded to the joint venture in May 2004, and exploration began in 2007 on block 5(c). On 20 February 2008, the Joint venture began operations on the second exploration well (Victory), with $290m spent on the project.
Challenger paid one third of the costs of the initial exploration programme on block 5(c) to earn a 25% interest in the production sharing contract, while Canadian Superior paid 26% and 40% to maintain 45% and 30% working interests, respectively. In 2007, BG Group signed a farm-in agreement with the joint venture to acquire a 30% interest in block 5(c).
In June 2009, Canadian Superior (now Sonde Resources) acquired Challenger Energy. BG Group increased its interest in the block to 75% through a joint operating agreement. In December 2010, Voyager Energy bought Sonde Resources’ 25% interest in the block. The sale was completed in June 2011.
Endeavour development
Challenger Energy, along with its partners, started drilling the Endeavour well on 28 August 2008. It was carried out using the Kan Tan IV semi-submersible drilling rig in 1,000ft of water.
The drilling process faced many challenges. After reaching a depth of approximately 16,921ft subsea in the final section of the well, drilling stopped due to a mechanical failure in Kan Tan IV’s drilling equipment – the travelling block. The fault was repaired by rig owner Sinopec and drilling restarted in mid-December 2008 in a separate section, as the previously drilled final section was no longer practicable due to well bore damage that occurred during the well control operations. Well control operations were initiated to manage an uncontrolled flow into the well during routine drilling operations while replacing a worn drill bit.
The Endeavour well was drilled to a final total depth of 17,426ft. The geological data obtained from the drilling indicates that the machine penetrated the main targeted zone and that the well encountered 162ft of gross reservoir quality sands over a 168ft interval.
Flow testing
Canadian Superior started extensive preparations of flow testing of the Endeavour well on block 5(c) at the end of January 2009 and testing began on 1 March 2009.
During the initial flowing period of 16 hours, a peak flow rate of 60.1 million standard cubic feet of gas a day was obtained – the maximum rate allowed under the testing equipment specifications.
A final flow rate of 56.4mmscf per day was measured using a 48/64in choke with a flowing well head pressure of 4,122psi.
Dry natural gas with a gas gravity of approximately 0.584 and 0.3% carbon dioxide flowed from the well, with no production of water and condensate or solids during the initial flow period.
