Harken steps up exploration in Colombia

• Harken's Colombian Acerage [25639 bytes]

Details of Harken de Colombia's accelerated exploration program are sketchy. But plans include:

• Drilling wildcats to evaluate 12 prospects covering a combined 75,000 acres, most of which have geology similar to supergiant Cusiana field under development by BP Exploration Co. (Colombia) Ltd. and partners.

• Conducting geologic and engineering studies of specific leads beginning next year on another 125,000 acres.

• Evaluating remaining acreage held under association contracts with state company Empresa Colombiana de Petroleos (Ecopetrol) to finalize plans there in the next 24 months.

Harken expects on average to drill one exploratory prospect per quarter beginning in 1997. The program also could include exploratory drilling to test new prospects identified through seismic and geologic studies and development drilling required by association contract terms.

Harken is talking with several drilling contractors about continually using one or more rigs the next few years for exploratory and possible development drilling. Rig availability in Colombia likely will become an increasing problem because recent large discoveries have heightened interest in exploring the country for oil and gas, Harken said.

Expanding presence

The company plans to finance the $60 million Colombian exploration program with cash on hand, funds generated internally, a $40 million European credit facility, and involvement of financial and industry partners.

As in the past, Harken intends to mitigate risk by including partners in the drilling phase of each prospect. The degree of interest among potential partners in the Harken's exploratory program could speed or slow the pace of drilling.

Harken in the past 3 years has stepped up geologic investigation of Colombia's Middle Magdalena and Llanos basins.

In terms of acreage held by association contracts with Ecopetrol, the company ranks third behind BP and Amoco Corp. among foreign companies working in Colombia, data compiled in Houston by Integrated Exploration & Development Services Ltd. (IEDS) shows.

Harken holds 100% interest in the following association contract areas:

• Alcaravan, a 22,214 acre tract acquired in November 1992 in the Llanos basin.

• Bocachico, a 181,940 acre tract acquired in March 1994 in the Middle Magdalena basin.

• Cambulos, a 311,593 acre tract acquired in September 1995 in the Middle Magdalena basin

• Bolivar, a 250,065 acre tract acquired in May 1996 in the Middle Magdalena basin.

Harken Colombian roundup

Harken has an active drilling program under way in Colombia.

The company in early September was using downhole pumps to production test 2 Torcaz wildcat in Bocachico contract area.

The exploratory well encountered 171 ft of net pay within a 1,065 ft interval including upper and lower Murgosa, Esmeraldas, and La Paz strata above 8,488 ft TD. Harken evaluated the Rio Negro test with a series of electric logs and completed the well open hole by setting 1,000 ft of slotted liner and gravel packing the open hole section.

Harken said 2 Torcaz porosity averaged 18.5% and oil saturation 50%.

Rio Negro is a 30,000 acre prospect first drilled by Texaco Inc. in the 1960s. Field structure is described as a northerly plunging anticline, limited on the western flank by a north-south fault.

The ResTech Houston unit of ResTech Inc., an independent petrophysical firm, in a 1994 study for Harken estimated Rio Negro reserves at as much as 200 million bbl of oil. Results of 2 Torcaz bear out the study's conclusions that Rio Negro porosity would average at least 18% and oil saturation 46%.

ResTech's study also reported Rio Negro's gross productive interval would total 1,000 ft and net pay about 100 ft. The company estimated Harken would have locations for as many as 200 development wells.

Other Colombian activity

Harken, meantime, has identified eight locations for possible Rio Negro development wells and has applied to Colombia's environmental ministry for permits to drill the first two.

Also in the Bocachico area, Harken late last month was drilling 1 Torcaz wildcat to 8,500 ft TD to test the same formations targeted by 2 Torcaz.

At last report, the company had set 20 in. casing to 140 ft, 133/8 in. casing to 940 ft and was drilling ahead at 6,682 ft, IEDS reports.

Harken in May filed permits to drill two other wells in Bocachico, both to spud in fourth quarter.

At Alcaravan contract area, Harken and 50% partner Huffco have identified oil potential in Cretaceous Gacheta strata. Partners in April 1996 suspended 1 Alcaravan wildcat at 10,550 ft TD after recovering water from two Ubaque zones at 10,292-305 ft, IEDS reports.

Harken in May 1996 asked Ecopetrol for permission to drill 2 Alcaravan wildcat to test Carbonera, Mirador, Guadalupe, and basal Cretaceous formations at about 10,000 ft on a seismically defined structure known as Palo Blanco.

Association contracts reviewed

Harken in February completed a 35 km 2D seismic program that identified several prospects and leads in Alcaravan.

Colombia's environmental ministry in July approved Harken's plan to drill the Palo Blanco test.

Harken in the first year of its Cambulos association contract is to reprocess 400 km of existing 2D seismic data. In the second year, the company must acquire 90 km of new 2D data and begin geologic studies based on surface information and satellite data.

Before starting the association contract's third year, Harken must cut its Cambulos acreage to 700 sq km. During the subsequent 4 years of the contract, the company must drill at least one well/year on the remaining acreage.

During the first 2 years of its Bolivar association contract, Harken is to reprocess 350 km of 2D seismic and acquire 100 km of new data. To retain rights to the Bolivar area, Harken the next 4 years of the contract must drill at least one well/year.

Copyright 1996 Oil & Gas Journal. All Rights Reserved.