Estimating Reservoir Properties and Well Performance Using Surface Production Data

Reliable and sufficient welltest data is necessary for the evaluation of reservoir properties and well performance. Best results a r e usually obtained by monitoring downhole pressure and flow rate continuously during a transient test. However, a recurring problem for geothermal welltests has been the failure of the downhole pressure instrument in the high temperatures and hostile environments, typical of these wells. Usually an incomplete set of data or data without downhole pressure is used for analysis which provides only limited or erroneous results. This paper presents a technique of applying a wellbore simulator and a reservoir simylator sequentially t o t h e surface data in order t o simulate the downhole condition during a flowtest, thus allowing estimation of the reservoir properties and well performance. Comparisons of the estimated results and the results obtained from the conventional welltest analysis indicate that this technique can provide a good estimate of the reservoir properties and well performance when downhole data is lacking.