Reservoir Boundaries relationship with respect to Reservoir Permeability
Mohsin Hassan
Senior Reservoir Management Engineer | EOR Lover | MSc Petroleum Engineer (Distinction Holder)
What the is the relation of Permeability with respect to boundary distances captured in PBU interpretation ?
We did two Pressure Build Up Surveys for 90 and 100 hours one after another. In first pressure build up survey which is of 90 hrs permeability value comes out to be 2.82 mD and the distance to the first barrier was 263 ft and distance to the second barrier was 551 ft. After production of 3 months, another pressure build up survey was acquired for a time period of 100 hrs. The permeability value decreased to be 2.16 mD and distance to the first barrier was 227 ft whereas distance to the second barrier was 416 ft.
According to radius of investigation r is directly proportional to k, so with decrease in permeability the distances captured in the first buildup should now not be captured or should be captured at a greater time. But the shape of the derivate plot still remains the same i.e. they over lay on each other with slight differences, and on interpreting it shows that the boundary distances has been reduced (as mentioned above). What can be the logic behind getting the boundaries at shorter distances with decrease in reservoir permeability? There is only one well in the field with gas condensate as fluid type and the reservoir pressure is still above dew point pressure.
Senior Reservoir Management Engineer | EOR Lover | MSc Petroleum Engineer (Distinction Holder)
5 年Ahmed Dawoud
Petroleum Engineer ????
5 年Personally I think the PTA will give u a deterministic outcome... Imagine that in the first PBU (shorter distance), pressure is travelling within a good quality sand. Hence, in average giving u relatively a good permeability. For the second PBU, with longer shut-in duration, the pressure is exposed to poor quality sand the extended of good quality before. When it comes to averaging, it will be less in term of permeability. Why the shape remain constant? Because the pressure is still travelling in the sand, but different quality. The best practice, after getting yourself convinced with PBU shape, try to sensitize with different permeability value to evaluate the potential boundary distance. On your map, draw the radius interpreted by PTA and discuss with G&G team should there is any potential statigraphic cut-off that causing that boundary phenomenon in PBU.
Manager Concept Development & valuations | Subsurface project leader | Lead Reservoir Engineer | concept architect @ Equinor
5 年Ali Cherif Azi I guess u r on one the few expert that could elaborate on this topic ...