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fax 01-972-952-9435. AbstractThe Handil field, discovered in 1974, is a giant mature oilfield located in the Mahakam Delta, Indonesia. The field consists of 555 accumulations and was developed by more than 350 wells with conventional oil recovery methods: natural depletion and peripheral water injection. After many reservoirs have been water-flooded, in order to recover the tertiary oil, EOR lean gas injection project was started in November 1995 on five reservoirs. The project was successful and extended to the other six reservoirs in 2000. However, the field production continued to decline from 200,000 BOPD in the late seventies to 12,500 BOPD in 2003.An integrated study on the largest EOR reservoir was performed to assess the projects' performance, including 3D geo-modeling, reservoir simulation and chemical tracer injection. The study permitted to track the main effects of the gas injection and define reservoir management guidelines for the other lean gas injection reservoirs.In the same time, dynamic synthesis has been performed in all accumulation in Handil Field with objective to identify potential "by-passed" oil and un-drained areas. Following the study, an intensive Light Work Over campaign has been launched and three pilot wells, each with different completion type, have been successfully put on production and became the model for the next Handil development wells; horizontal well equipped by gas lift to recover viscous sandy reservoir in very shallow zone, gravel pack equipped by ESP to recover sandy reservoirs in shallow zone and monobore multi-target well equipped by gas lift to recover reservoirs in main zone.The production has been increased by nearly 100 percents, from 12,500 BOPD in 2003 to 23,000 BOPD nowadays. Integrated reservoir study and the successful application of Light Work Over and Infill Well to recover "by-passed" oil and un-drained areas, supported by EOR techniques to maintain the reservoir pressure and sweep the tertiary oil, become the key elements to revive the mature Handil Field.

The Khuff Formation is a major reservoir in Qatar and the rest of the Middle East Gulf region, and contains some of the world's biggest gas reserves. Geologically the carbonate platform system is complex with fine-scale heterogeneities which impact the static and dynamic reservoir characteristics. These heterogeneities are depositional, stratigraphic and diagenetic in nature and therefore reservoir characterization needs to be an integrated multidisciplinary and multiscale approach. In order to address these issues a large multidisciplinary and multiscale subsurface study has been launched on a large database including fields from across the region. The aim is to better understand the facies distributions, sequence stratigraphic architecture and the regional reservoir development, in order to better characterize dynamically reservoir behavior.

Handil is a mature oil and gas field discovered in 1974 and developed since 1975. The field extends on a 40km2 area and includes hundreds of stacked hydrocarbon accumulations. Firstly produced by natural depletion, water injection was then implemented as an improved oil recovery mechanism to sustain the oil production and enhance the waterflooding.. From 1995 to 2007, tertiary recovery mechanism was implemented with gas injection. In 2007, with increasing oil price it has been decided in 2007 to resume EOR opportunities in Handil, an Alkali-Surfactant-Polymer project has been initiated. A pilot project of Chemical EOR Injection had been initiated in 1980-s but had to be suspended few years later due to technical reasons and low oil price. In order to evaluate this EOR method potential, remaining stake evaluation was done with different residual oil saturation measurements (coring, logging, SWTT). First analysis lead to very low oil residual saturation: Gas effect with possible tertiary flooding and fresh water flooding are the main hypotheses to explain these results. A screening of the EOR techniques applicable in Handil ended up with the suggestion to test surfactant polymer injection into a wareflooded reservoir. Therefore as a first step an assessment of residual oil saturation was critical. To properly evaluate the volume at stake it was first essential to determine range of remaining oil saturation into water flooded reservoirs. It has been decided to use two different approaches: a first one via existing wells based on the technique of Single Well Tracer Test (SWTT), the second one being coring of the reservoir nearby the tested area investigated by the SWTT. Both approaches gave similar results. However preparation of a SWTT campaign in a mature field environment was challenging. Facing the importance of the measurement, long preparation time was taken to ensure that residual oil saturation values found are reliable and representative. Due to field maturity where most of existing well integrity is questionable, requirement to perform integrity test of the well candidate was compulsory. A hydraulic test and a mutifinger imaging tubing run were done ending with what was assumed to be the qualification of 4 wells out of 5 initial candidates. Indeed SWTT have been successfully performed into reservoirs accessible via the some qualified existing old producers. However interpretation of the data raised several questions. Consequently it has been decided to investigate whether tracers had been placed into the right reservoir. Investigation was performed using Water Flow Log technique that helped understanding where the tracers went and also the well integrity status behind casing. Three (3) Water Flow Logs have been run into the wells with uncertainties. Combination of the hydraulic test, multiimaging tool and water flow log, helped discarding 1 (one) out the 4 (four) wells due to unexpected communications behind casing. Thanks to these operations EOR project could go forward with reliable remaining oil saturation measurement, key value for project design, and with a certified qualifying procedure to be applied on any future existing old well susceptible to be used by the project.

fax 01-972-952-9435. AbstractThe Handil field, discovered in 1974, is a giant mature oilfield located in the Mahakam Delta, Indonesia. The field consists of 555 accumulations and was developed by more than 350 wells with conventional oil recovery methods: natural depletion and peripheral water injection. After many reservoirs have been water-flooded, in order to recover the tertiary oil, EOR lean gas injection project was started in November 1995 on five reservoirs. The project was successful and extended to the other six reservoirs in 2000. However, the field production continued to decline from 200,000 BOPD in the late seventies to 12,500 BOPD in 2003.An integrated study on the largest EOR reservoir was performed to assess the projects' performance, including 3D geo-modeling, reservoir simulation and chemical tracer injection. The study permitted to track the main effects of the gas injection and define reservoir management guidelines for the other lean gas injection reservoirs.In the same time, dynamic synthesis has been performed in all accumulation in Handil Field with objective to identify potential "by-passed" oil and un-drained areas. Following the study, an intensive Light Work Over campaign has been launched and three pilot wells, each with different completion type, have been successfully put on production and became the model for the next Handil development wells; horizontal well equipped by gas lift to recover viscous sandy reservoir in very shallow zone, gravel pack equipped by ESP to recover sandy reservoirs in shallow zone and monobore multi-target well equipped by gas lift to recover reservoirs in main zone.The production has been increased by nearly 100 percents, from 12,500 BOPD in 2003 to 23,000 BOPD nowadays. Integrated reservoir study and the successful application of Light Work Over and Infill Well to recover "by-passed" oil and un-drained areas, supported by EOR techniques to maintain the reservoir pressure and sweep the tertiary oil, become the key elements to revive the mature Handil Field.