In this paper, we discuss the use of the dynamic material balance (DMB) method to a super-giant carbonate oilfield. The principal advantage of the DMB method, in contrast to the conventional material balance (CMB) methods, is that well shut-ins are not required for the application of the DMB method. While the fundamental assumptions of material balance are still applicable, we extend the DMB method described in the literature in several important ways. These extensions include:
The use of pressure dependent oil formation volume factor (FVF), Bo, including a pressure dependent oil compressibility, co
The use of pressure dependent (net effective confining stress) formation compressibility, cf
The use of a revised method for estimation of the original-oil-in-place, OOIP
Due to the significance of a super-giant oilfield to the operator's portfolio, well shut-ins are routinely performed in the field and stabilized, static shut-in pressures, though not required for the application of the DMB, are commonly collected. Consequently, we are in a position to compare the results of the DMB predicted pressures to field measured pressures. In general, these comparisons are very favorable, and they will be presented and discussed in the paper.
In addition to the use of the DMB for original-oil-in-place (OOIP) estimates, we have observed that trends in the DMB plots can be used to diagnose pre-/post- workover performance. Therefore, we can use the DMB method to determine the success/failure of well interventions for improving the well productivity and for adding connected in-place oil to the wellbore. Our experience with this application of DMB will also be discussed in the paper.
Finally, we use this paper as a case study for the application of the DMB method to a producing oilfield.