oa The Evolution of Kinabalu Reservoir Modelling, “from Multiple to Single”

The Kinabalu field is located offshore Sabah, 55 km KM WNW of Labuan Island. The field was discovered in 1989 by well KN- 1, which found several stacked Late Miocene reservoirs. The reservoirs are late Miocene sediments deposited in the upper to lower shoreface environments. The hydrocarbon accumulation occurs in a 3-way dip closure monocline in the hanging wall of a SW-NE trending growth normal fault. The Kinabalu field consists of is made of three accumulations, the Main, the Deep and the East, that contain 500 mmstb STOIIP. The STOIIP of the field is 500 MMstb, 80% of of which is oil in place located in the Main accumulation. Development of the Kinabalu field started in 1997 with development drilling of the Main accumulations. First oil was in December 1997. Historically the reservoirs in the Main accumulations were modelled individually owing to . This approach was followed because of limitations in computing power and because modelling packages at that the time could not handle listric dipping faults. Static and dynamic modelling were challenging since multiple models needed frequent updates had to be updated all the time which require extensive staff and computer time. This required lot of man power and consumed lot of time. Well planning using multiple single models was another challenge since a typical well in Kinabalu wells typically have has several targets. Also In addition, use of Excel spreadsheets to reconcile reconciliation of simulation output from individual models into a full field output was done using Excel spreadsheets, which made auditing difficult almost impossible and often introduced several errors. With The significant improvements in computing power and the advances ment in modelling packages and the push by the leadership team asked for a modelling approach combining that could combine simplicity and speed. meant a To achieve a new way of doing things, had to be found. The the team, therefore, came up with the idea of a “Kinabalu Mega Model”. The Kinabalu Mega Model (i.e. KMM) incorporates all the 35 oil-bearing reservoirs in the Main accumulations, . There are 35 stacked reservoir which are modelled in KMM, covering the depth range from about 4000 to 10000 ft tvdss. The aerial dimension of the model is 25000 ft x 8000 ft. Prior to upscaling, the static model has 3 million grid cells that are . The size of each grid cell before upscaling is 300 ft x 300 ft x 4 ft. After upscaling for dynamic modelling the size of each grid cell is 300 ftx300ftx 18 ft. In terms of static modeling workflow, this new mega model enables a better handling of structural uncertainty since all the reservoirs are now share an integrated into the same structural framework. Subsequently, the sensitivity to petrophysical properties across all reservoirs in different structural realizations can be tested. The model also provides a common platform for members of subsurface team and requires fewer people to maintain the project. This contributes to time saving and better data management. process. From the dynamic point of view, the availability of the KMM has simplified and speed up history matching and forecasting. Wells with completions in multiple reservoirs can be simulated with better accuracy than previously. Planning of future development activities are now very transparent to all multi-discipline team members. Lastly, we now have a very efficient tool for full field management. In conclusion the main contributions of the Kinabalu Mega Model are summarized below: 1. Increase modelling speed, which translates into time saving. <br>2. A simplified and transparent modelling methodology which requires less man power, yet still retains accuracy. 3. Uncertainty ies modelling and data management are handled in a very efficient way. 4. The mega model has also given the team the holistic view when it comes to future development in Kinabalu. (The team used to look at individual parts of the field).