Predicting horizontal well flow rates under the geological conditions of Western Siberia fields
Research relevance. The determination ofthe expected wellflow rate is a key problem in designing the development of oilfields with horizontal wells. In industrial practice, actual and realflow rates of horizontal wells usually differ significantly. Research objective. The algorithms for horizontal well potential flow rates determination have been studied extensively. However, the issues of choosing a methodology for determining the flow rate in relation to particular geological conditions remain unresolved. It is necessary to compare the actual and design rates of horizontal wells and identify the most representative methods forflow rates determination for the geological conditions of Western Siberia fields. Methods of research. A single horizontal well draining a semi-infinite reservoir is considered in the absence of hydrodynamically isolated and poorly drained zones within the radius of the well external boundary. The Giger, Joshi, Janar, and Renard-Dupuy methods were used to determine the expected flow rates of horizontal wells only under the following conditions: a homogeneous reservoir and a near-rectilinear horizontal section of the well in the reservoir interval. As an example, the calculation of the expected flow rate of a horizontal well with the following initial data is given: the horizontal section length is 700 m, the net oil thickness is 7.8 m; the permeability coefficient is 127 • 10-15 m2, oil viscosity is 1.24 MPa • s, the drawdown is 3 MPa, the external boundary radius is 1000 m, and the volume factor is 1.08. Results. Quite significant discrepancies between the actual and design data are recorded for wells with arbitrary numbers 4, 7, 8, 10, 15, 18 and 20. All the methods used for calculations provided comparable results. For all other wells, the calculation results have a high convergence with field data. Conclusions. The Giger, Joshi, Janar, and Renard-Dupuy methods may be recommended for horizontal wells expected flow rates determination only under the following conditions: a homogeneous reservoir and a near-rectilinear horizontal section of the well in the reservoir interval.