Road-boring rig to aim at viscous Texas oil

June 28, 2006
A West Texas operator will use a modified road-boring rig to drill two multilateral horizontal pilot wells to access shallow viscous oil in Wardlaw field in the Val Verde basin.

By OGJ editors
HOUSTON, June 28 -- A West Texas operator will use a modified road-boring rig to drill two multilateral horizontal pilot wells to access shallow viscous oil in Wardlaw field in the Val Verde basin.

The rig will be equipped with modern directional drilling tools to intersect the Cretaceous Glen Rose formation at about 300 ft, said operator United Heritage Corp., Midland, Tex. This will allow the rig to spud the wells at high angle.

The contractor that will plan and supervise the Wardlaw wells has used the technique successfully to dewater coalbed methane wells in Kentucky and in heavy oil projects in Venezuela, said UHC and its Lothian Oil Inc. affiliate.

UHC said it committed more than $1 million to drill the wells in August and September.

Wardlaw field, in Edwards County 25 miles west of Rocksprings, Tex., has 27 active vertical wells producing 10-15 b/d of 20-25° gravity oil from Glen Rose, in which the primary recovery mechanism is gravity drainage. Another 17 wells are available for production by either adding pumping equipment or by swabbing.

A typical 7-7/8-in. vertical well bore has 20-30 sq ft of reservoir surface area exposed over the 10-15 ft of pay interval, but the planned 4-1/2-in. multilaterals will have 6,000-8,000 sq ft of exposure, UHC said. The multilaterals will alter the flow pattern from radial flow to a combination of linear and radial flow.

Each horizontal well is expected to develop 40 acres, and Lothian estimated that the acreage has the potential for as many as 250 horizontal wells. Each well is to cost $500,000, go on production at 25-50 b/d, and yield 25,000 bbl.