Modern advancements in technologies pertaining to the drilling of horizontal well and multi stage hydraulic fracturing have made it possible to get significant hydrocarbon production even from extreme low permeability formations. However, correct evaluation of the economics of the project is becoming increasingly essential before committing to any big investment. In this scenario, production forecasting based on reservoir simulation plays an important role by not only evaluating the economic feasibility of the project, but also helping in the selection of the most optimal development strategy. In this paper, a workflow has been demonstrated that proved useful in addressing such challenges related to the tight reservoirs (permeability less than ~2mD).

The methodology adopted in this study can be divided into two parts. The first part involves data preparation for single well numerical modeling similar to Daungkaew et al (2008) and Kumar et al (2008). This includes building a petrophysical model based on the mineralogy characterization and also carrying out Rate Transient Analysis (RTA) for permeability estimation using the data acquired from an existing well (Pan et al, 2011). RTA is preferred over the conventional buildup analysis as it does not require shutting of the well. The second part of the workflow involves creation of a numerical model based on the petrophysical, PVT and SCAL data. Hydraulic fracture (if present) is modeled by editing the permeability of the grid cells falling under the fracture geometry. The model is calibrated with the production data after initializing with the pressure and fluid contacts. The history matched model is then used to generate production forecasts of multiple scenarios including horizontal well with multiple stages of fracturing and sensitivities can be made with respect to drainhole length, fracture stages etc. Furthermore, economic analysis can be carried out to select the most economically viable case.

The proposed workflow has been applied in one of the low permeability oil field in India. The permeability derived from RTA was in close agreement with the core results. This workflow was used to generate production forecasts for multiple development scenarios. It was used to optimize the number of fracture stages, keeping the drainhole length constant.

In this paper, a novel approach is discussed that combines the RTA and single well numerical modeling technique to evaluate different strategies of producing from a tight reservoir. Based on the economic analysis then, one can maximize the return.

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