With the increasing difficulty of discovering new Iranian oil reserves, attention is necessarily focused on the efficient development and production of existing reservoirs. One of Iranian fields (field "A") with about 28 kms length and 4 kms width was explored in 1963 with drilling well No.1. The Asmari reservoir consists of a mixture of high permeability sands and carbonate section in elongated anticlinal structure. It confirmed the oil potential for the Asmari reservoir. However, in field "A" before any reservoir oil production occurred in 1974, the reservoir pressure was observed to drop. This phenomenon has been investigated to determine if Asmari communication exists between "B" and "A" oil fields. In 1973, field "B" Asmari oil production reached a peak of around 1.1 MMBPD, and the apparent field "A" Asmari reservoir pressure drop was circa 100 psi. A practical analytical method has been used in this paper which provides the practicing reservoir engineer with a handly method for analyzing oilfield interference problems. Attempt has been made to apply this method on these actual fields. It is concluded that aquifer of field "A" has strong communication with field "B".
One particular situation in which analytical techniques are needed involves studies of multiple, water-drive oil fields sharing a common aquifer. Such oil fields are in hydrodynamic communication. Therefore, production from any of the oil fields is accompanied by a pressure decline which is transmitted through the aquifer to the other oil fields and manifested as pressure interference. The rate of propagation of the pressure decline is such that the pressure may be significantly reduced many miles away from a producing pool.
The procedure employed to treat oil fields in interference entails the principle of superposition. Mathematically, the superposition theorem states that the linear combination of particular solutions to a linear and homogeneous differential equation is a solution to the differential equation. The superposition theorem is a useful tool for treating systems upon which involved boundary conditions are imposed. The general solution is the summation of the particular solutions obtained by treating one boundary condition at a time.
The transient flow of compressible liquid in a uniform porous matrix is described by the diffusivity equation, which is linear and homogeneous and therefore is subject to superposition. It follows, that the performance of multiple oil fields in a common aquifer can be evaluated from the separate solutions obtained by dealing with one field at a time. In essence, if the pressure change associated with producing each and every field were computed individually(i.e. ignoring the presence of all oil fields but one) for a time instant, t, and at some arbitrary point in the reservoir system, then the total pressure change at this point and time instant is given by the sum of all individual changes. For that matter, the arbitrary point may well be the effective center or any other appropriate point in an oil field, and the time instant may represent some assigned future date at which it is desired to predict the behavior of the system.
