[Need Help] Least Distance to Sealing Fault

[elevenfourth]

Hello guys,

I would like to ask something about sealing faults. As we've known, if we drill a well too close to a sealing fault, the drainage would not be really beneficial, and only small amount of oil would be drained.

What I want to ask is : Is there any rule of thumbs of the least distance of a well from a fault so that it would be beneficial to drain oil?
Or, is there any equation or formula to calculate the minimum/least distance from a well to a fault?

Thanks in advance!

[DAH7542]

Well, being honest I don't know about any rule of thumb or calculation to (i.e. equation) to get that. However, I''ll give you my opinion based on theoretical concepts of Pseudo-Steady State productivity index (PSS PI). Based on the works of Dietz (SPE 1156) and Watenbarger (SPE 39970), the highest PSS PI is that of a well draining from the center of a circular drainage area. For any other drainage area shapes the PSS PI is lower. As for the well position within the drainage area, a centered well will provided a higher PSS PI than an off-centered well. And this last observation is the important point regarding to your question: based on PSS PI theory, wells must be placed far enough from no-flow boundaries (e.g sealing faults) to ensure maximum PSS PI.

I suggest you read the papers and make sensibilities of PSS PI based of the well position within the drainage area, of course you should have an idea of what the size and shape of the drainage are is (ask you geologist if you dont know or check this by yourself).

Hope this helps.

[abdou2403]

JUST A POINT OF VIEW OF GEOLOGIST,

What I know as exploration geologist is that we choose the well position 200 m to 300 m far from the interpreted fault on seismic section.

the reason is that the fault is not in fact only one plane or surface, but many planes, it is a fault zone. So we try drill further enough to avoid

problems while drilling (mud lost, tool sliding,), and also to avoid the risk of missing the target if the seismic quality is not good enough.

For the case of channel bar which means two parallel faults for reservoir engineers, as geologist I target the mid channel bar because I'll meet more sands.