| Abstract |
Constant producing pressure solutions that define declining production rates with time, for a naturally fractured reservoir, with transient interporosity flow are presented. The solutions for the dimensionless flow rate are based on a model presented by Cinco-Ley, Samaniego and Kucuk. In this work the model was extended to include constant producing pressure in both infinite and finite systems. The results obtained for a finite no flow outer boundary are new and surprising. Similarly to Da Prat et al.1, it was found that the flow rate for conditions of fracture skin greater than 10, shows initially rapid decline, becomes nearly constant for a period, and then a final decline in rate takes place. The same criterion established by Da Prat et al.1 for the estimation of the outer radius of a reservoir, , requiring that the almost constant flow rate period be reached by the data is applicable to the present transient interporosity flow model. However, the estimation of from this method is higher for fixed values of the and parameters. A field example is presented to illustrate the method of type curve matching for a naturally fractured reservoir with transient interporosity flow. The values of and are determined from the best match and this is particularly important for the case of production forecasting by numerical simulation. The results show that the initial decline could be a key factor in deciding whether to complete or abandon a well, and for a practical viewpoint, given an initial value for the flow rate, it is important to know the time required to deplete the two porosity system. |