INVICTUS Energy, which is exploring for oil and gas in Muzarabani, has achieved a fantastic result from the Mukuyu-1 and sidetrack well which has multiple gas zones and potentially liquid hydrocarbon bearing intervals, managing director Mr Scott Macmillan has said.
The firm is, however, not able to make any formal declaration of gas and oil discovery as that process requires that the firm obtains a fluid sample.
In a statement released by the firm yesterday, Mr Macmillan said there is a proven hydrocarbon system in the Cabora Bassa Basin “as evidenced from significantly elevated gas shows and fluorescence during drilling and confirmed the presence of rich source rock, seal, reservoir, trap and timing.”
“Whilst we are frustrated with the numerous operational challenges encountered and not being able to obtain a fluid sample which would have enabled the formal declaration of discovery, we have still achieved a hugely significant result from the first well in the basin which has substantially de-risked our dominant acreage position and established a new petroleum province.
“We have gathered a high-quality dataset across the Mukuyu-1 and sidetrack well which will now be integrated with the existing seismic data to calibrate and refine our interpretation and plan for the appraisal of Mukuyu as well as additional prospects in the basin,” Mr Macmillan said.
The wireline log interpretation calculated porosity of up to 15 percent and gas saturation of up to 90 percent in selected potential pay zones but are yet to be calibrated with fluid and core data and subsequently subject to wide margins of error.
Meanwhile, Invictus has decided to conclude operations at the Mukuyu-1 well as fluid samples are not obtainable at the Mukuyu-1 well due to technical and operational issues.
The fluid samples are critical as these would serve the company to make a formal declaration of discovery of commercial oil and gas in the basin.
In the update, Invictus said drilling was now focused on Mukuyu-2 and the Exalo Rig 202, which was brought to the drilling site in July last year, will remain on site for a year to enable drilling of future sites in the basin.
The first well-drilling at the Mukuyu-1 prospect commenced in September last year.
During the course of drilling operations at Mukuyu-1 well, the drill string was rigged up to conduct fishing operations to attempt to retrieve the wireline formation testing tool.
The drill string with the overshot was run in hole to the casing shoe to commence installation of the side entry sub to allow for wireline operations through drill pipe without interference from the rig’s top drive system.
“However, during the installation process the T Bar clamp broke and operations were suspended until a replacement T Bar could be sourced from a regional supply base resulting in several days of delays. The company said after the arrival of a replacement T Bar clamp, the side entry sub was successfully installed and fishing operations resumed.
“The wireline cable was successfully freed, however, the wireline formation testing tool became stuck against the borehole wall during the intervening period.
“The tool was successfully engaged with the overshot but required significant force (approximately 50,000 foot-pounds) to break the tool free and the tool is unsuitable for use until it can be assessed and repaired,” said Invictus.
Following mechanical disconnection of the wireline cable, the tool was successfully retrieved to the surface.
At present, the primary and backup wireline formation testing tools are non-functional and the duration to repair or replace the equipment is unknown.
The logging conditions evidenced by tool and drillpipe sticking and significant overpull observed during fishing operations also render conditions unsuitable to make further attempts to obtain a fluid sample even with functioning wireline tools.
“Subsequently, further attempts to obtain a fluid sample are not feasible and the company will conclude operations on Mukuyu-1 and ST1 and demobilise the well services equipment and personnel.
“Rig 202 will be warm stacked at the Mukuyu-1 well location to allow for maintenance and upgrades prior to recommencing drilling at either Mukuyu-2 or Baobab-1 in 2023 following sourcing of required long leads and tendering of well services and equipment,” said Invictus.
Laboratory analysis of sidewall cores acquired during logging and drill cuttings and mudgas samples acquired while drilling will provide further calibration of the wireline and the geological model once completed
“Invictus and Exalo Drilling S.A (Exalo) have executed a contract amendment for Rig 202 to remain in the Cabora Bassa Basin in Zimbabwe for up to 12 months to enable the drilling of future wells in the basin.
“The highly encouraging results from the initial Mukuyu-1 and sidetrack well have provided the company with the confidence to keep Rig 202 warm stacked at the Mukuyu-1 location whilst preparations are made for the future drilling campaign for at least one firm well in 2023, with further wells to be agreed. – The Herald
