Implementing a proactive approach with comprehensive reservoir characterization, risks identification and mitigation are key elements that have to be deeply investigated before the project execution for achieving the optimum results in field development. A tremendous result on the seismic driven field development and synergy with a fast track development concept in Merakes green gas field has been achieved. In this paper, the conceptual and methodologies are described in the way of managing the subsurface risks and uncertainties during the planning and execution phase. A suitable example in Merakes field development which classified as "appraisal while developing", since the remaining risks still exist during development campaign, is presented. By having only two exploration wells with limited data, a robust upfront reservoir characterization and modeling were quite challenging to provide a reliable image of the subsurface condition. The enhancement on the way of constructing an integrated reservoir study prior to the field development is considered an essential requirement that has to be done before the project execution. A comprehensive approach that maximizes the integration of Geology, Geophysics and Reservoir Engineering disciplines and brings out the reservoir risk quantification has been considered as a basis and strategic driver for both subsurface quantitative description and de-risking of development wells locations. Focusing on the subsurface risk criticality, the compartmentalization, rock facies quality, gas-water contact depth and sand production were considered as the main critical aspects that could impact the final success. Preserving mitigation strategies and adapting development flexibility concept have been prepared to overcome such subsurface unexpected conditions. A description of the well placement strategy which widely open to be optimized during the drilling campaign was allowed and brought benefits in mitigating the compartmentalization risk. The readiness of an adequate and comprehensive data acquisition program including log data acquisition, coring and well testing in the development wells has been prepared. Moreover, a sidetrack contingency plan has been also considered for a key-well in case of worse than expected results. With know-how and experiences on the nearby field development, an extensive evaluation of water and sand production risks was derisked by selecting smart completion and sand control technologies. A holistic integration between subsurface, drilling, petroleum, facilities disciplines is considered of paramount importance in development projects. The awareness of the field's risks and uncertainties allows maximizing efforts in following up the drilling phase promptly adapting the data acquisition plan to the effective level of residual uncertainty and related development risk. Eventually the good match between the expected scenario and the actual well results allowed to cancel most of the costly data acquisition plans which contributed to a positive impact on the project cost and time-saving.

Prediction of the presence, distribution and quality of deep water reservoir requires integration of all subsurface disciplines (Geology, Sedimentlology, Geophysics, Petrophysics, Operational Geology and Reservoir Engineering). Complex environments of deposition and reservoir architectures must be understood by integrating all disciplines to ensure optimal resource development and hydrocarbon recovery. The case study is located in Kutei Basin, East Kalimantan, Indonesia. The subsurface description is challenging because the field is a system of individual hydraulically discrete reservoir ЉsegmentsЉ not all of which have been penetrated. Several subsurface challenges have been identified using all subsurface data (seismic, core and log) in order to optimizing the development drilling campaign and for developing the production strategy.Seismic attributes are used to delimit the segment boundaries and thickness, determining the impact of seismic tuning has been particularly important in understanding reservoir geometry uncertainties. The extensive series of 3D seismic processing attribute extractions, seismic interpretations and supportive studies have been utilized to design a drilling sequence, well placement and formation evaluation plan that will reduce uncertainty/risk in the drilling campaign process.All exploration wells encountered gas within Pliocene deep water turbiditic sandstones characterized by staked, very thin to moderately thick bedded sandstone bodies separated by thick to very thick intervals of shale and siltstones. Those sediments are product of submarine canyon fill. Generally, the sandstones have good to excellent reservoir properties (porosity 0.22-0.30 with permeability Ͼ100 mD).The other challenge is that the reservoirs consist of thinly bedded sandstone-siltstone and shale, where the conventional log analysis can underestimate hydrocarbon pore thickness and volume in such beds. It will impact static and dynamic modeling for gas in place calculation. Hence, thin beds analysis should be performed to obtain reliable interpretation by using proper logging tool and method.The results of characterizing and mitigating the risks have been applied in the planning and execution of development wells during drilling campaign of the case study and is considered successful finding good quality sandstone reservoirs. Development of deepwater gas fields in Indonesia is in its early stages. The depositional environment is challenging due to the number of separate reservoir systems included in a single development. Limited well control requires heavy reliance on seismic interpretation of two different data sets.

In 2009, a Gas reservoir discovery was made in the Deepwater of the Kutei Basin offshore East Kalimantan, Indonesia. The appraisal campaign continued through 2012 delineating both a main field (Jangkrik) and a satellite field to the north (Jangkrik NE). Three well tests were conducted during the appraisal phase confirming good permeability and high gas deliverability. Geologically, the field is characterized as a slope channel turbidite deposition system made up of many separate reservoirs. Some of the reservoirs amalgamate together in a channel complex system. The development scheme entails eleven subsea wells tied-back to a FPU for offshore processing of gas and condensates. The project is currently in execution phase and the development drilling and completion campaign is ongoing.In October 2014 the first development well was drilled. The well was drilled from one of four drill centers in the north of the main field targeting for development two reservoir segments. Both segments will be completed using smart completion and frac pack to manage the potential for sand production during the production. This paper describes the integrated approach to model the clean-up design to optimize the cross discipline objectives and make critical decisions during the operational clean-up on the rig.The clean-up design has been carried out to capture all possible reservoir risks related to the type of depositional. Not only the standard well testing software tool has been used, but also a 3D reservoir model has been developed to be able to predict the reservoir behavior during the clean-up and the build-up period. Furthermore as a validation the reservoir modeling is implemented to compare these two results using the well testing software. As the conclusion, this analysis helps the operators determine the best and proper way to operate the well and to prepare for the commissioning phase.Deepwater gas development projects require reliable and consistent gas well deliverability to satisfy gas production targets and gas sales commitments. The clean-up of the high rate gas wells is critical after a successful completion to both establish the actual deliverability but also to minimize the production of completion fluid through the subsea system and to the FPU facility. The clean-up design was developed to meet all objectives for the project.Development of Deepwater gas fields in Indonesia is in its early stages. The project is challenging due the number of different and separate reservoirs to be developed. Each well is designed to intersect and complete at least two reservoirs isolated and monitored separately through two Down-Hole Gauges (DHGs) that are installed in the intelligent completion design. The clean-up phase will utilize the intelligent completion equipment to clean-up and to test each reservoir independently.

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Rock typing is a technique of grouping rocks that have similar properties, which properties can be in the form of sedimentary, petrophysical, and reservoir parameters. Classification based on sedimentary parameters is called sedimentary rock type (SRT), while grouping based on petrophysical parameters is called petrophysical rock type (PRT). The purpose of this study is to determine the relationship between SRT and PRT in the research area. The method used to determine sedimentary rock type is to use the facies concept approach, while the method used to determine petrophysical rock type is the Hydraulic Flow Unit Method, Global Hydraulic Element, Winland R35, and Pore Geometry Structure. In this study, determined the relationship between sedimentary rock type with petrophysical rock type, where some facies that have certain characteristics will have a certain type of petrophysical rock type pattern. Thoroughly bioturbated mudstone facies which have low porosity and permeability have two petrophysical rock types with initial sequence (RT 1 and RT 2) with the HFU, GHE, and Winland R35 methods, while with the PGS method there are RT 4 to RT 7. These facies have low rock type variations, it can be concluded that these facies are homogeneous