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Collaborating Authors
Results
Application of Integrated Reservoir Analysis to Optimize Development Plan
Wang, Shie-Way (Unocal Indoensia Company) | Shivers, Jon Blake (Unocal Corporation) | Setiawan, Yusak H. (Unocal Indoensia Company) | Inaray, Jossy C. (Unocal Indoensia Company) | Harmawan, Iwan Suganda (Unocal Indoensia Company) | Fidra, Yan (Unocal Indoensia Company)
Abstract This work presents a methodology which uses nodal analysis, material balance, pressure transient analysis, and integrated production management (IPM) to determine reservoir boundary, original fluid in place (OFIP), and completion strategy for one of the reservoirs in West Seno field, the first deepwater development project in Indonesia. The drainage area calculated from pressure test analysis compares favorably with that derived from seismic amplitude map.OFIP was used to (1) guide 3D simulation to study the potential of secondary recovery with water or gas injection and (2) build an IPM model to study optimal workover strategy. Although reservoir size and OFIP were evaluated with various methods, the final results are very similar.This finding and successful history matching with IPM and 3D simulation models increase our confidence in the optimized development plan. Introduction This paper discusses competing development plan for the reservoir with longest production history in West Seno field, offshore Indonesia.The reservoir designated as S1024๏ผฟER5 has two active production wells, a downdip D5 and an updip D6, which started their first production in August 2003.D6 has an initial oil rate at 8800 B/D and D5 at 4400 B/D.The rate plateau lasted for one month and then followed by rate decline accompanied with higher GOR. Fortunately, there is no detectable water production to date although oil-water contact is identified in downdip well, D5. The development plans include (1) moving either D5 or D6 uphole to develop shallower horizons, (2) potential of water flood to increase ultimate recovery, and (3) moving one well uphole with or without commingled production from current horizon, S1024. Geology The West Seno Field, which is the first deep-water development in Indonesia, is located within the Makassar Strait PSC offshore Kalimantan, Indonesia. This field is about 60-km from the shore line as shown in Figure 1.Unocal discovered this field in 1998 after drilling and testing the West Seno-2 exploratory well.There have been fourteen subsequent delineation wells drilled to prove economic accumulation of hydrocarbons.West Seno WSA-D5 and D6 are part of 28-well development program from the West Seno TLP-A. The field lies in 2400 to 3400 feet of water on the continental slope of the northern Mahakam Delta approximately 50-km to the ENE of the Giant Attaka Field.The Seno Structure is an elongate, four-way dipping, faulted anticline covering an area of approximately 70 sq. km. West Seno WSA-D5 and D6 are intended to develop the oil & gas reserves associated with the Upper Miocene deeper pay zones established in the WS-2 discovery well.Several of these zones were flow tested in the WS-2 well.Seno-102/104 sands were tested at a rate of 2,950 bopd + 3.1 mmcfg. The Upper Miocene reservoir sands in the West Seno area were deposited in a deepwater, intraslope basinal setting, very proximal to the Upper Miocene paleo-shelf margin.In general, the reservoir architecture indicates these sands are associated with turbidite deposits.These sands are laterally amalgamated, multi-stacked channel and channel-levee deposits, which provided numerous stratigraphic trapping components. The productive interval penetrated by D5 and D6 is devided into two stratigraphic units vertically as S102 and S104.Figure 2 shows the structure top of S102 and the well positions of D5, D6 and the appraisal well WS-2.The Type logs of D5 and D6 with demarcation of S102 and S104 are shown in Figures 3 and 4, respectively. Reservoir Study Reservoir study consists of three parts:material balance method, pressure transient test, and development plan, which are described in the following sections.Simulation and integrated production model (IPM) were used to determine best development strsategy as pressure declines with time.
- Asia > Indonesia > Kalimantan (0.95)
- Asia > Indonesia > East Kalimantan > Makassar Strait (0.95)
- Asia > Indonesia > East Kalimantan > Makassar Strait > Kutei Basin > West Seno Field (0.99)
- Asia > Indonesia > East Kalimantan > Makassar Strait > Kutei Basin > Attaka Field (0.99)
Abstract A method was developed to estimate the composition of heavy end by matching MDT pressure gradient when downhole sample or reliable recombined surface sample is not available.After adjusting the heavy end or C7+ composition, an equation-of-state was used to match (1) MDT pressure gradient from calculated gas density, (2) dew point, (3) surface condensate yield, and (4) API gravity of condensate.The fine tuned equation-of-state was then converted into a pseudo black oil PVT table.This method allows reservoir engineers to study production from retrograde gas condensate reservoirs without using equation-of-state to handle complex phase behavior and commingled production from multiple reservoirs. Three examples are included to illustrate the proposed method.The first two examples give detailed description of step by step procedures.The third example incorporates a 3D reservoir simulation model and a pipeline to form an integrated model.The reservoir model consists of two separate reservoirs to be produced by two subsea wells, which are linked to a surface pipeline tied back to West Seno FPU.The advantages and disadvantage of this method are discussed at the end of this paper. Introduction This paper presents a method which tries to estimate liquid yield and phase behavior when there is lack of good downhole sample but good MDT pressure gradient is available.If we have good downhole sample or good recombined surface sample, the fluid composition and phase behavior can be determined in laboratory.However, if downhole sample is not available or only the composition of separator gas is available, then the true reservoir fluid composition can not be accurately determined. The main difference between a downhole sample and a separator gas sample is the missing of heavy end or condensate in separator gas.The mole fraction of C7+ in a good downhole sample, assuming no contamination, is known with certainty and should not be adjusted during regression of equation-of-state (EOS).On the contrary, separator gas is devoid of heavy end or C7+. Therefore, the main objective of this method is to estimate the mole fraction and/or molecular weight of the heavy end, C7+, so that the adjusted composition will yield a gas density at reservoir condition to match MDT pressure gradient.The adjusted fluid composition is considered to represent the true composition at initial reservoir condition.
- Reservoir Description and Dynamics > Unconventional and Complex Reservoirs > Gas-condensate reservoirs (1.00)
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Phase behavior and PVT measurements (1.00)
- Reservoir Description and Dynamics > Fluid Characterization > Fluid modeling, equations of state (1.00)