Equivalent Wellblock Radius for Partially Perforated Vertical Wells--Part I: Anisotropic Reservoirs With Uniform Grids
- Ali H. Dogru (Saudi Arabian Oil Company)
- Document ID
- Society of Petroleum Engineers
- SPE Journal
- Publication Date
- December 2010
- Document Type
- Journal Paper
- 1,028 - 1,037
- 2010. Society of Petroleum Engineers
- 5.1.1 Exploration, Development, Structural Geology, 5.1.5 Geologic Modeling, 2.2.2 Perforating, 5.5 Reservoir Simulation
- equivalent wellblock radius, well modeling, numerical reservoir simulation, reservoir simulation, reservoir modeling
- 1 in the last 30 days
- 574 since 2007
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The well index in a numerical reservoir simulator relates the flow rate to the difference between well flowing pressure and simulator gridblock pressure. The standard method for computing well index, Peaceman's formula (Peaceman 1978), requires an equivalent wellblock radius at which the gridblock pressure is equal to the pressure from an analytical solution for steady-state single-phase flow. Although Peaceman?s formula is accurate for fully penetrating vertical wells, it fails to account for the effect of vertical flow in partially penetrating wells.
In this paper, we present a new analytical expression for the equivalent wellblock radius in a homogeneous, anisotropic reservoir with a uniform square grid around the well path. The new equation has the same structure as Peaceman's equation but adds one new parameter to account for partial penetration and for vertical flow. The new formula reduces to Peaceman's formula when the well is fully penetrating. Model simulation study showed that the new method reduced the error in the calculated flow rates from 30% to less than 1% at minimal cost.
|File Size||564 KB||Number of Pages||10|
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