Results from TT-29w, the latest well to be drilled in the field, have proved an oil water contact (OWC) to be 145m deeper than estimated pre-drill at this location, implying that more oil could be recovered from the flanks of the field than currently planned.
At its peak, Taq Taq was producing over 100,000 bopd, but from late 2015 rates declined dramatically and by Q3 this year production averaged 14,080 bopd. As a result, the gross 2P reserves were downgraded from 172mmbbls to 59 mmbbls in March 2017.
Taq Taq is a fractured Cretaceous carbonate reservoir, which relies on the presence of natural fractures to deliver production. Genel had planned to develop the field by drilling and producing wells in the crest of the reservoir, where fracture density is greater and rates are higher. However the decline in production was due to the rapid watering out of these wells and subsequent surveys demonstrated that the water level is now higher in the crest than in the flanks. This variation in OWC across the field implies that there is bypassed oil sitting in the flanks, where the presence of fewer fractures are thought to have limited the water influx.
TT-29w was designed to appraise the northern flank of the field and the confirmation of a deeper OWC here is encouraging, though the company will need to see production history in order to fully assess the potential of the flank. It is possible that there could be similar upside potential in the south flank, but this would need to be confirmed with a well. The 2017 CPR assigns 1P reserves of 10mmbbls to the flanks, with a value of $20m, implying around $2/bbl for flank oil ( on a NPV15 basis and assuming the oil price increases to US$70/bbl by 2020). Since this figure is based on pre TT-29w data, this could be increased if production data and further flank wells confirm the deeper OWC.
The influx of water is a common and known issue for fractured reservoirs worldwide, whether in carbonate reservoirs, as typically seen across the Middle East, or in basement reservoirs such as that seen in Hurricane Energy’s Lancaster field West of Shetland. With proper mitigation and management measures however this need not be of concern.