Sperry performs pressure tests in North Sea and GoM

Halliburton's Sperry Drilling Services has had two recent success with its GeoTap while-drilling formation pressure tester, part of the company's Stellar formation evaluation suite.

The GeoTap logging-while-drilling (LWD) formation tester obtains direct pore pressure as the well is drilled, with accuracy and precision comparable to that of wireline formation testers, Halliburton says. The tool transmits real-time pressure data to surface via the mud column and records the data to memory for more detailed analysis. The device allows multiple tests to be performed in a single drilling run.

According to Halliburtion, the 6 3/4-in. GeoTap LWD sensor was the first commercially available pad/probe while-drilling formation pressure tester for 8 1/2-in. to 10 5/8-in. hole sizes. The 8-in. tool has now performed pressure tests for Statoil in Norway and Unocal in the Gulf of Mexico.

Statoil's Tordis/Vigdis team used the 8-in. formation pressure tester offshore Norway to measure formation pressure while drilling in a 12 1/4-in. by 13 1/2-in. section. The tool took more than a dozen pressure readings, communicating reservoir data up hole and allowing the operator to make fast and accurate decisions regarding the testing program.

Statoil says the company needed to have early information about communication in the reservoir, which the GeoTap tool provided. This LWD formation pressure technology allows the operator to gain valuable pressure information in complicated well paths during the drilling process, Statoil says.

The GeoTap tool also recently saw its first success in the GoM on Unocal's deepwater Mississippi Canyon block 941 well. The GeoTap tester took five pore pressure measurements in five attempts.

2/24/05