Publications

Trekulu-1 (TKU-1), located 35 km to the East of Balikpapan, and 40 km to the south of Peciko field is the first well drilled by TOTAL in the South-East Mahakam PSC. The well was drilled to a TD of 4935mMD (4,897.2mTVDSS) from 15/03/2010 to 25/11/2010, in HP/HT conditions, 195°C and 900 bars at TD. The objective of the well was to prove gas resources within an untested turbiditic sand system in the Mid Miocene Yakin equivalent interval (primary objective). Upside prospectivity was identified in the Mid Miocene Sepinggan Deltaic Sequence equivalent series. The main identified risks were, -1- the presence and deliverability of reservoirs, and -2- the drillability, in a very narrow drilling window environment above the reservoir objectives, due to a very steep pressure ramp leading to very high shale & pore pressure for both objectives. The closest well, Manggar-1, drilled by TOTAL in 1971 reached its TD at 3,100m on a well control event, in this pressure ramp. The Trekulu-1 well was safely drilled through its objectives down to TD. There was no HSE incidents, no well control, no side track, even though drilling conditions through the pressure ramp were more complicated than expected, and drilling was longer than expected. Key to successful operations were the preparation and the close collaboration of all involved. The well was thoroughly prepared using TOTAL HQ worldwide expertise on HPHT wells. During operations, close * TOTAL E&P INDONESIE communication and team work between well construction and geoscience teams, as well as TOTAL and rig contractor personnel enhanced follow-up capability and reactivity. Lessons learnt include, -1- a heavy architecture with contingencies was mandatory, -2- Managed Pressure Drilling (MPD) was a must: TD would not have been reached without MPD, and -3- MW and gas management strategy had to be adapted, to properly discriminate ballooning and gains, and to properly assess pore pressure. The main objective encountered more than 100m of very fine to fine grained turbiditic sand with several reservoir levels of fair to good petrophysical characteristics, confirming the pre-drill sedimentological depositional model. The lack of hydrocarbons in the Yakin equivalent reservoirs could be explained by, -1- an insufficient charging of the trap, due to limited quantity and quality of organic matter in the turbiditic sands, -2- or/and a breaching of the top seal, due to hydraulic fracturation and / or up-fault leakage. Drilling of TKU-1 well was both a geosciences and an operation challenge. Unfortunately, the well was not successful in the Mid-Miocene Yakin equivalent turbiditic play, even though reservoirs were found. But the successful operations have demonstrated that even most difficult HPHT wells with narrow drilling windows wells can be drilled safely to TD, opening new perspectives.