Invictus Energy Ltd. encountered hydrocarbons while drilling the Mukuyu-2 well in license SG 4571, Cabora Bassa basin, Zimbabwe.
The well spudded Sept. 20 to test the Triassic Upper Angwa formation, sitting about 450 m updip from Mukuyu-1 where hydrocarbons were intersected. The well also penetrated multiple additional targets including the previously untested Lower Angwa sequence within the Mukuyu anticline in the central horst structure (OGJ Online. Sept. 21, 2023).
Drilling of the 8 ½-in. hole section reached 3,718 m MD where section TD was called. The 8 ½-in. hole section has reached the current depth of 3,296 m MD.
Strong gas shows (up to 65 times above background gas baseline), with associated drilling breaks and fluorescence in cuttings (indicative of presence of liquid hydrocarbons) have been encountered in multiple additional Lower Angwa sandstone reservoirs from 3,296 m MD to TD. High levels of trip gas were observed when drilling recommenced along with increasing levels of connection gas during drilling which necessitated raising the mud weight to maintain the required pressure overbalance in the borehole.
No logging while drilling (LWD) resistivity or gamma ray data was available since drilling recommenced due to a failure of the backup pulser. As a result of increasing levels of connection gas, drilling mud weight would need to be increased further to continue drilling beyond current TD, and a decision was made to call TD at 3,718 m MD to commence wireline logging to evaluate multiple zones of interest in the current 8 ½-in. hole section.
The post drilling borehole condition after drilling to TD and pulling out of hole remains good and conducive for conventional wireline logging operations. Current wireline logging operations will provide an evaluation of the 8 ½-in. hole section.
Invictus Energy managing director Scott Macmillan said that “Mukuyu-2 has proved up over a 1,000 m gross interval of hydrocarbon charge through the Upper and Lower Angwa formations across multiple reservoir zones. The planned comprehensive wireline logging program including formation pressure and fluid sampling, sidewall cores and checkshot surveys will be run with the aim of confirming the presence of moveable hydrocarbons in multiple zones in the Upper and Lower Angwa formations to declare a discovery.” He said the company expects to complete the wireline logging program in the next 6-8 days depending on logging conditions and number of fluid sampling stations.
Invictus is operator with 80% interest.