Publications

Tunu Gas field has been producing gas from Tunu Main Zone deep reservoirs (> 2500 mss) since 1990 with a plateau gas production around 1.3-1.4 Bscf/day.In 2009-2010, a new 3D seismic survey (396 Sqkm - 44 km x 9 km) so called Central Tunu 3D (CT3D) was acquired by ELNUSA contractor on Tunu field operated by TEPI (Total E&P Indonésie) with INPEX as partner.The main objective assigned to this new seismic was to properly delineate the shallow gas-filled channels of Pliocene age (target window between 600 m - 2200 m) in order to properly perform further seismic reservoir oriented processing and studies for assessing new economic reserves and optimizing well locations for future Shallow Gas Plans of Development (POD).A set of High Density (HD) seismic parameters was specially designed to meet these technical objectives: Fold 72 - bin 12.5m x 12.5 m - max inline offset 2400 m - max crossline offset: 1600 m. Cross spread acquisition 12 cables roll 6.This seismic was located in the transition zone (TZ) of the Mahakam delta. In such a TZ, the main operational constraints are related to:- A highly variable environment from shallow sea to rivers and flooded land all submitted to tidal variations- Dense population and fishing economy: the area was occupied by 3 main villages with 1,500 fishermen working on 800 producing fish ponds.A multidisciplinary team named “Task Force was specially built for obtaining permits from authorities and facilitating the integration of the project with non TEPI (Total E&P Indonésie) stakeholders.To support seismic activities, the Task Force conducted and coordinated many actions on the field such as socialization with villagers, compensation policy for works in fish ponds, compensation agreements with local authorities, environmental monitoring, organization of security forces around sensitive areas, coordination with Marine (commercial or belogging to TEPI), etc...But Tunu is also a giant gas field (80 km x 20 km) congested with many man-made structures (production surface facilities, pipelines, etc.), under intensive development (ca. 70-80 development wells drilled per year). On a day to day basis many wellservicing activities are also required on field wells to maintain and/or to optimize gas production.The imprint of the seismic spread is a “carpet of 18 cables (3.4 km x 9 km) with 12 active cables for recording and 6 inactive cables which are used for rolling continuously over the field . The seismic progress followed a NNE - SSW direction.Throughout its duration the seismic acquisition was confronted with large drilling activities (about 75 wells prepared and drilled in this period), and about 1000 well-servicing interventions.In such a context, active and daily coordination was critical with all field operations, in order to avoid having barges or rigs within the active seismic spread. For management and coordination purposes, a specific planning tool was specially built for all field operations (dredging for rig moves, conductor pipe driving, drilling within shallow gas section, drilling within reservoir section, well connection, completion) and this was updated twice a week.The planning was built in 2D for a better understanding of all entities: one axis for the time and the other axis for Seismic progress and well locations. All well locations and related operations were projected and updated regularly on this seismic progress axis from NNE to SSW (swath 134 to swath 93).During a total of 285 recording days (12 hour/day)the coordination was very effective with very little stand-by time: 12.3 hours for permitting issues (in shrimp pounds and a short blockage before project termination), 6.2 hours for field operations (no planning conflict: but incidents with a “lost barge) and two short SIMOPS with Rigs. Most of the stand by time (87.35 hours) was related to bad weather conditions.Despite the high complexity of the task, this operation was a great success for technical, HSE organization and coordination with local communities and TEPI producing entities. Local communities fishermen and villagers were all involved in socialization and supported the seismic activities for security, surveillance and decommissioning. A survey carried out among the population after the seismic operationsdemonstrated a rather good image and positive impact of overall seismic activities conducted by TEPI in the Area.This project was a first large scale experience successfully conducted in the Mahakam producing area and a good omen for future seismic activities already planned in the same area in 2011-2013.New organizations and methods had to be invented by Project Management team and some Total corporate procedures had to be updated or even created.The lessons learnt will serve the whole Total group.