Unocal Announces Ranggas Test Results
The Ranggas-4 appraisal well flowed at a daily rate of 8,158 barrels of oil and 6.4 million cubic feet of gas from a single interval between 10,174 feet (3,101 meters) and 10,224 feet (3,116 meters) true vertical depth subsea (TVD). The drillstem test had flowing tubing pressure of 1,223 pounds per square inch on a 56/64-inch choke.
The test rates were constrained by test equipment, but initial daily production rates from a well producing from this single zone are estimated at upwards of 10,000 barrels of oil and 8 million cubic feet of gas.
The Ranggas-4 well encountered 181 feet (55 meters) of net oil pay and 57 feet (17 meters) of net gas pay. The well was drilled in 5,208 feet (1,587 meters) of water to 11,252 feet (3,430 meters) TVD. The well is located 2.4 miles (3.8 kilometers) north of the Ranggas-1 discovery well and 1.2 miles (1.9 kilometers) south of the Ranggas-3 appraisal well.
"The oil test rates are impressive, and we are very encouraged at this point in our appraisal program," said Brian Marcotte, president of Unocal Indonesia Company. "The test results are another step towards commercializing our third deepwater oil field in Indonesia."
Marcotte said the company plans to spud the Ranggas-5 appraisal well, also on the main Ranggas structure, before the end of April. With the results of the Ranggas-4 well, Unocal currently estimates the gross discovery volume for the main Ranggas structure is about 200 to 350 million equivalent barrels of oil, with additional potential in other prospects on the same trend. Earlier, Unocal had estimated the unrisked exploration potential of the entire Ranggas complex at 350 to 650 million equivalent barrels of oil. Unocal has now drilled six wells in the Ranggas complex, and all have discovered hydrocarbon potential.
Two wells were drilled recently to test structures on both the north and the west parts of the large central Ranggas prospect. The Ranggas Utara-1 well encountered 33 feet (10 meters) of net oil pay and 44 feet (13 meters) of net gas pay. The well was drilled in 5,258 feet (1,603 meters) of water to 12,650 feet (3,856 meters) TVD. The well is located 2.5 miles (4.0 kilometers) north of the Ranggas-3 well. This accumulation was deemed sub-commercial as an independent development at this time, but demonstrates the potential for additional hydrocarbons to the north of the Ranggas field.
The Ranggas West-1 well encountered 85 feet (26 meters) of net gas pay in two intervals. The well was drilled to 9,955 feet (3,034 meters) TVD in 4,483 feet (1,366 meters) of water. The well is located 2.9 miles (4.6 km) west of Ranggas-3. This accumulation could most likely be tied back to the future Ranggas development facilities via a single subsea well. Oil potential remains in the southern extension of this trend.
Marcotte added that several additional prospects on trend or adjacent to the main Ranggas structure remain to be drilled. This includes the Api prospect where the Api-1 well is currently being drilled.
Unocal Rapak is operator of the Rapak production-sharing contract area.
It holds an 80-percent working interest, while Lasmo Rapak, Limited, a subsidiary of ENI, holds the remaining 20-percent working interest.