THE DRILLING OF PALM VALLEY –2 WELL, AMADEUS BASIN, NORTHERN TERRITORY, USING AIR AS THE CIRCULATING MEDIUM

Abstract

Magellan Petroleum (N.T.) Pty Ltd's Palm Valley -2 was spudded in on 21st December 1969 and reached total depth of 6559 feet on 2nd February 1970. The well was completed as a gas well after flowing at the rate of 69.7 MMCF per day during testing.

Hole and casing sizes were: 26 in. (20 in.) 31 ft; 17½ in. (13⅜ in.) 431 ft; 12¼ in. (9⅝ in.) 4225 ft; 8½ in. (7 in.) 6057 ft. The rig used was a National 100 and in addition to 6 in. O.D. and 8 in. O.D. drill collars 3 x 11 in O.D. and 6 x 9¼ in. O.D. were run for drilling down to 4225 feet.

Compressed air was used as the circulating medium. The air equipment major components comprised: -

2 Ingersoll Rand 1500 cfm primary compressors

1 Ingersoll Rand 1500 psi booster compressor

1 12 in.−3000 psi Shaffer rotating BOP.

15 Rock bits were used in the drilling of Palm Valley −2. Substantial water was encountered while drilling through the Mereeinie Sandstone which is a major aquifer of the region.

The 7 in. casing was set at 6057 ft and drilling below this point to total depth (6559 ft) was carried out with 2⅞ in. production tubing, 4¾ in. drill collars in conjunction with OTIS N nipple, XO sliding-door sleeve and X landing nipple. This string was used as a combination drill out/production assembly and was left in the hole as a completion string after removing the sliding sleeve with the wire line. A Cameron LDO 2⅞ in. control head was installed prior to drilling out the 7 in. shoe.

The use of air as a circulating medium on Palm Valley −2 clearly demonstrated the economic and operational advantages of this drilling method. There are undoubtedly other favourable geological areas in Australia where this drilling and completion procedure could be adopted to great advantage.