ADX Energy Limited has finally plugged and abandoned Sidi Dhaher 1, in the Chorbane license, Tunisia, after a DST exercise in which 90 barrels of mud filtrate and formation water were recovered. The well has now been plugged and abandoned.
It’s not clear whether sheer incompetence or unbridled optimism led to the wasteful testing. ADX’s announcement did not say that logs were interpreted before the DST was carried out. “The test results are in apparent conflict with the previous analysis in the fall of 2011”, the company explains on its website. Still ADX beat its chest in an announcement: “Despite good flow rates from the two reservoir zones and substantial amounts of fluids being produced fromthe upper reservoir zone, the fluids were not observed to contain any quantities of oil”, it says in a release.
“Following the drilling out of the safety plug within the previously suspended well, two separate intervals within the Bireno Formation have been perforated and flow tested. A 5 meter section within the deeper Bireno Dolomite interval was perforated between 3,852-3,868 feet (1,174-1,179 meters) Measured Depth (“MD”) together with a 16 meter section in the shallower Bireno Limestone interval between 3,789-3,842 feet (1,155-1,171 meters) MD”, according to the release.
“Approximately 90 barrels of fluid were recovered which were identified as most likely consisting of a mixture of drilling mud filtrate and possibly formation water. The efficient recovery of these fluids during the test suggests that they were sourced from the deeper Dolomite interval.
Although a large volume of fluids have been lost to the formation while drilling and in preparation for the test, and the total volume had not yet been recovered during the flow test, the Joint Venture participants agreed to plug off the deeper Bireno Dolomite section and test only the shallower Bireno Limestone section in isolation.
“After performing a cement squeeze to close the perforations over the deeper Bireno Dolomite interval, and the setting of a bridge plug within the well-bore and between the Bireno Dolomite and the Bireno Limestone intervals, a flow test of the Bireno Limestone interval commenced. Prior to acid stimulation of the reservoir, no liquid flow from the Bireno Limestone was observed and an acid stimulationwas undertaken”.
The release concluded that “following completion of the acid stimulation, the well was flow tested, with the benefit of nitrogen lift and approximately 680 barrels of fluid were recovered over a flowtest period of 35 hours. The initial interpretation from the well site is that the recovered fluid is a mixture of spent acid, drilling mud filtrate and formation water”.