Anglo African Oil & Gas plc, an independent oil and gas developer, is pleased to provide an operational update following the successful results from drilling the TLP-103C well at the producing Tilapia oil field in the Republic of the Congo.
This update sets out details of the Company’s plan to re-enter TLP-103C and seek to bring the Djeno reservoir into production.
Overview of the operational plan
The Company will seek to bring the Djeno into production by re-entering well TLP-103C and drilling a sidetrack just below the Mengo horizon. This sidetrack will be designated TLP-103CST1 and will initially deviate away from TLP-103C for a short distance before continuing vertically downwards. This design reduces the risk of shifting too far from the original location where the Company logged positive results.
TLP-103CST1 will vertically intersect the Top Djeno and then continue into the Middle Djeno, which was below the total depth of TLP-103C. Once the Middle Djeno has been tested, the Company will determine whether the Djeno can be brought into production from either horizon. In parallel, limited but necessary upgrades will be carried out to the topside facilities to ensure that the Company can produce from the well immediately following testing.
Technical details of the drilling plan
TLP-103CST1 is designed as a low side sidetrack. A land drilling rig will be used to clean out the 9 5/8″ casing down to the current casing shoe depth at 2,100m measured depth (MD), using seawater with hi-viscosity mud sweeps. The well will then be displaced to a potassium chloride polymer water-based mud system, and a casing pressure test will be conducted to 80% of the casing burst rating. A further 5m of the original 8 ½” hole will be cleaned out, and a formation integrity test will be performed prior to drilling out the remainder of the lower cement plug to re-enter the previous 8 ½” open hole.
In preparation for drilling the sidetrack, a new cement plug will be set inside the 8 ½” open hole below the 9 5/8″ casing shoe. The kick-off plug is designed to have a compressive strength in excess of the formation strength to allow for successful kick-off operations.
The 8 ½” hole sidetrack will be drilled directionally from a planned kick-off point of 2,200mMD (approximately 100m below 9 5/8″ casing shoe). Drilling parameters have been defined to achieve a 3 degree/100ft dogleg, dropping angle from 35 degrees to 0 degrees inclination, maintaining the same azimuth to attain a ±200m step out compared to TLP-103C at the same true vertical depth.
The 8 ½” hole section will continue to be drilled vertically down to an approximate target depth of 2,900m true vertical depth (TVD), through both the upper and middle Djeno reservoir targets.
Drilling through the reservoir sections will be carefully monitored so that the differential pressure will be maintained at a minimum 100-200psi above hydrostatic pressure so as to minimise formation invasion and minimise the potential for loss of circulation
A comprehensive suite of formation evaluation logs will be acquired across the Top and Middle Djeno reservoirs, including resistivity, sonic, density-neutron, spectral gamma ray, formation pressures, formation samples and mechanical sidewall cores will be retrieved.
Following this, a 7″ liner will be run and cemented across the open hole interval in readiness for producing the Djeno reservoirs. Using High Shot Density perforation guns, the Djeno reservoir will be perforated prior to running the Completion string. Assuming that all results at this stage are positive, the well will be flowed tested and cleaned before putting TLP-103CST1 on production, utilising the existing surface facilities.
The Company has posted on its website two technical drawings which illustrate the above plan.
Planning of operations
The Company has identified two suitable drilling rigs, both currently situated in the Republic of the Congo, which have drilling slots available this year. The company is evaluating commercial offers from both rig companies and will update the market once the chosen rig is contracted.
As stated above, the Company intends to minimise the scope of initial works in order to control capital costs ahead of drilling TLP-103CST1. Following these initial works, the topside facilities are estimated to be able to handle the production of approximately 2,000bopd. The Company is, however, developing plans to further improve the topside facilities based upon several different levels of potential future production, with the exact plan to be finalised only once actual flow rates are known.
The Company confirms that the court in the Republic of the Congo has lifted the seizure order obtained by SMP against certain of the Company’s subsidiary’s assets.
The Company will provide further updates on the above operational points and plans in due course.
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