Previous studies on horizontal well applications for bottom water drive reservoirs mostly assumed no pressure loss within the horizontal wellbore in predicting the performance. Except at low rate production, such an assumption could lead to over estimation of the oil production. The results are therefore not conclusive yet. Since it is a high cost technology, a plan of reservoir development with the use of horizontal well requires optimization of the acreage and production rate. The real challenge then and thus the main objective of the present study is to investigate the effect of drainage area and rate of production on the oil recovery. This work employs a semi-empirical method that has been successfully validated using field data. The method can also be used to evaluate the effect of wellbore length and its position and reservoir anisotropy on the production performance.
Results obtained show that, for the same well length and same withdrawal rate, the fractional oil recovery decreases with increasing well acreage. Also found here is that the rate of recovery can be enhanced by withdrawing a higher volume of produced fluids although breakthrough time for water is shortened. By taking this advantage, a larger spacing therefore can be overcome by increasing both production rate and the length of horizontal wellbore section proportionally to achieve a high oil recovery for a shorter production period. These findings have not been previously reported and are of importance in relation to the economic point of view of reservoir development. Results also demonstrate that a higher oil recovery may be obtained by use of a longer horizontal well section. The effect of wellbore placement on the recovery along with other results will be discussed in detail.
The ultimate goal of this paper is to provide engineers the strategy for Optimizing the development of bottom water drive reservoirs using horizontal wells. A simple procedure for forecasting the production performance is clearly presented.