Equipment difficulties force GulfSlope to stop drilling at Tau prospect

  • Exploration & Production

GulfSlope Energy has decided to abandon its well at the Tau Prospect in the U.S. Gulf of Mexico – without reaching targeted depth – in a way that will allow re-entry due to equipment limitations and rig’s other contractual obligations. 

GulfSlope started drilling its initial subsalt exploration well in the Gulf of Mexico on the Tau prospect on Ship Shoal Blocks 336 and 351 in September 2018, using the EnscoRowan-owned Ralph Coffman jack-up drilling rig.

GulfSlope encountered difficulties with the well in December 2018 associated with shallow faults requiring two additional casing strings prior to setting 13-5/8 inch casing above salt.

By February 2019, the Tau well was drilled through approximately 7,000 feet of salt where high pressures and hydrocarbons near the base of salt were encountered, and significant mud losses occurred. The interval was treated with lost circulation materials and cement.

In a statement on Monday, May 13 GulfSlope said that the well was drilled to a measured depth of 15,254 feet, as compared to the originally permitted 29,857 foot measured depth. Producible hydrocarbon zones were not established to the current depth, but hydrocarbon shows were encountered.

The company explained that complex geomechanical conditions required two by-pass well-bores, one sidetrack well-bore, and eight casing strings to reach the current depth. Equipment limitations prevent further drilling at this time. In addition, the drilling rig has contractual obligations related to another operator.

Namely, according to EnscoRowan’s latest fleet status report, the Ralph Coffman rig is scheduled to start a contract offshore Trinidad with an undisclosed operator in June 2019, which will last until October. After that, the rig is due to start a contract with CGX in Guyana until December 2019.

Due to these factors, the company has elected to abandon this well in a manner that would allow for re-entry at a later time. The drilling, pressure, and reservoir information has confirmed geophysical and geological models, and reinforces the company’s confidence that there is resource potential in excess of 300 million barrels of oil equivalent remaining in the untested zones, GulfSlope said.

The company also said it is currently evaluating various options related to future operations in this well-bore and testing of the deeper Tau prospect.

The Tau well is designed to test multiple Upper and Middle Miocene sand series targets over a 14,000 foot vertical depth section down the flank of a salt feeder stock, and below the base of an associated salt sheet. The correlative target subsalt Miocene sand levels are oil productive at the nearby subsalt Mahogany Field, located approximately five miles to the southwest.


Corvette Prospect plan approved 


Meanwhile, the company’s Exploration Plan (EP) related to Vermilion Area, South Addition Blocks 375 and 376 (Corvette Prospect) was recently approved by the United States Department of the Interior, Bureau of Ocean Energy Management (BOEM).

The application for the Permit to Drill for this well is in progress and will be filed with BOEM in May 2019. The company anticipates executing a rig contract for the drilling of the Corvette Prospect in May 2019.

The Tau Prospect is the first of eight drill-ready exploratory prospects that the company intends to drill along the Louisiana Outer Continental Shelf, targeting the substantial oil potential of the subsalt Miocene play. By applying advanced seismic depth imaging technology and geoscience modeling, GulfSlope intends to achieve its goal of discovering large new oil and gas fields.

GulfSlope is the operator of the Tau well with a 20 percent working interest. Delek GOM Investments LLC, a subsidiary of Delek Group owns a 75 percent working interest and Texas South Energy owns a five percent working interest.

Offshore Energy Today Staff

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