Naturally fractured reservoirs are more difficult, complex and expensive to evaluate using numerical simulation when compared to conventional reservoirs. There are well known approaches, dual porosity and dual permeability system in which two grids - one for the fractures and another one for matrix – are used to model the behavior of fracture reservoirs characterized by initial high production followed by a steep decline and then low production for many years. However, most of the time these approaches require a large amount of input data in addition to being computationally too expensive and time consuming in field applications utilizing many grid blocks to model. This paper presents a new pseudo-approach in which a single porosity model can be used for modelling of naturally fractured reservoirs with some modification in the absolute permeability and relative permeabilities. The absolute permeability of the single porosity model is enhanced to capture the effect of permeability from the fracture. This can be a multiplier globally applied to all blocks or local enhancement around the wells having high fracture intensity. Initially the flow is mostly coming from the fracture network so the first "fracture dominant" relative permeability or combination of fracture/matrix relative permeability is used, and later in the lifetime of the reservoir, when the flow transitions to primarily matrix flow, a second "matrix dominated" relative permeability is used to control the fluid flow. The key in this approach is to find the time/date which flow diverted from fracture to matrix. This can be determined from the overall oil rate of the field. After finding the correct date, then the relative permeability is altered from "fracture dominant" to "matrix dominant" recurrently on that time. The new approach is applied to an onshore matured field in Indonesia. The numerical model has the total grid blocks of 1.2 million, 75 wells and around 700 thousand active grid blocks. The original single porosity model could not match the field historical data while dual porosity could captured it correctly. Numerical simulation is utilized along with the new method in a single porosity model for history matching of the field and the results are compared with the dual porosity model of the same model. The absolute permeability enhancement and the first relative permeability curves are used as matching parameters. The results of this study show that both models having same/similar production and pressure profile. Liquid rate, oil rate, water cut, GOR and average pressure are compared. Furthermore, the runtime for the field case improved by 75%. The total runtime of the new approach was 22 hours resulting in significant speed-up compared to the dual porosity runtime of about 4 days. This approach is going to be used for few other fractured reservoirs in the future where time and/or fracture data are limited.

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The brain of a waterflood project is a geological framework that defines reservoir continuity relative to its transmit fluids as well as restrict fluid movement. The lack of geological knowledge results in the misleading interpretation and understanding of the reservoir behavior. This paper presents an integrated geological aspect, concept and approach to design an effective well pattern and well spacing in waterflooding. This method is proven to improve sweep efficiency and lead us to make an EOR planning in our field. T Field is one of the mature fields where a successful waterflood project has been implemented in Indonesia Detailed core description with sedimentary structure analysis, paleocurrent analysis in FMI data and various property maps were conducted to identify the relationship between injection and production well. It also gives the information about movement of injected water. The sediment transport suggests some directional anisotropy in permeability. The distribution of geological heterogeneities and their influence on fluid flow characteristics were determined by generating maps and cross sections based on integration of log, core & petrographic data and qualitative information from production data. Parameters mapped included the distribution of porosity, log derived geometric mean permeability, clay content, and Dykstra-Parsons coefficients of permeability variations. The results of this study showed a good correlation of facies distribution and sedimentation direction with flow of water movement behavior. The direction indicated relatively west to east sediment transport being perpendicular to the structure. It was also matched with tracer survey analysis and simulation model. In our success story, we applied the staggered line of full scale waterflood pattern to maximize the areal sweep efficiency and improve 5-7% recovery factor of total OOIP. This information also strongly supports the building of reliable static and dynamic model. We proved that an integrated geological approach, including a good understanding of facies and sedimentation characteristics of reservoir will lead us to build successful waterflood and EOR project in the future.

In Tanjung, South Kalimantan, PT Pertamina EP (PEP) use secondary recovery (waterflood injection) for its technique for oil lifting. Low permeability reservoir condition make quality of water injection must be comply with low permeability reservoir requirement and the pressure injection must be around 1400 psig. In the common PEP injection plant, carbon steel pipeline is still used. Flakes accumulation and trapped oil could occur along with the deterioration of carbon steel pipeline. This matter can make the quality of requirements of injection water become worst. There were four data were analyzed; Oil content, TSS (Total Suspended Solid), Turbidity and Total Iron. The sample was taken at discharge pump and one of the injections well during 6 months.  Averagely the result of value of total iron, turbidity and oil content in injection well are bigger than discharge pump while TSS has little fluctuation. In conclusion, deterioration carbon steel pipeline has effect to reduce quality water injection become worst and effect of roughness of pipeline due to carbon steel deterioration can make the pressure drop is higher in accordance with the length.