Good day Professor Martin, I just wanted to thank you for this video, the format is really great and a big improvement on your old videos which are also terrific! As a Subsurface Engineering student I can't tell you enough how helpful your videos have been.
Dear Professor Martin Blunt thank you for this great explanation,I have a question about the behavior in that we have trouble saturation for the same distance is that because we neglect the capillarity and the gravity term from the fractional flow?.Because at a low saturation where the saturation gradient decreases again, the capillarity is so high so it might be neglecting this capillarity force will lead the gradient to be lower again
I am not quite sure what you mean. Yes, we ignore capillary forces but we do not need to neglect gravity. Capillary forces will smear out the shock front, leading to smaller saturation gradients. You can have a constant saturation though even if capillary forces are considered.
@@BoffyBlunt thank you professor,what I meant is neglecting capillary leads to that Behavior of triple saturation and drawing tangent is just like we reconsider the capillary effect because these low saturations should have high capillary pressure based on pc vs sw. In the other hand I have another understanding from your lectures on UA-cam is that the shock we developed represents advective flow and the capillary has no contribution in that shock. In summary my question is can I give this physical reason of the neglecting capillary pressure lead the low saturations to advance slow where we get triple saturation. I’m just trying to understand why do we have triple saturation or in another context why the fractional flow curve behave as it is when we neglect capillary pressure. With regards
@@hamzaalyaseri6047 The fractional flow as a function of saturation does ignore capillary forces. As I said previously, the inclusion of capillarity tends to smear out the shock. I do not understand what you mean by "triple saturation": the fractional flow is always a single-valued function of saturation.
@@BoffyBlunt thank you professor for your patience and fast response, i will change my question to : why the shape of Sw vs distance takes this shape, is there is any physical reason or its just math problem ?
@@hamzaalyaseri6047 It is always both - consistent with the maths and physically-sensible. Since the wavespeed for low water saturations is low, a shock develops. In reality this shock is smeared out by capillary forces, but there is a sharp change in water saturation at the leading edge of the water front.
Good day Professor Martin, I just wanted to thank you for this video, the format is really great and a big improvement on your old videos which are also terrific! As a Subsurface Engineering student I can't tell you enough how helpful your videos have been.
Dear Professor Martin Blunt thank you for this great explanation,I have a question about the behavior in that we have trouble saturation for the same distance is that because we neglect the capillarity and the gravity term from the fractional flow?.Because at a low saturation where the saturation gradient decreases again, the capillarity is so high so it might be neglecting this capillarity force will lead the gradient to be lower again
I am not quite sure what you mean. Yes, we ignore capillary forces but we do not need to neglect gravity. Capillary forces will smear out the shock front, leading to smaller saturation gradients. You can have a constant saturation though even if capillary forces are considered.
@@BoffyBlunt thank you professor,what I meant is neglecting capillary leads to that Behavior of triple saturation and drawing tangent is just like we reconsider the capillary effect because these low saturations should have high capillary pressure based on pc vs sw. In the other hand I have another understanding from your lectures on UA-cam is that the shock we developed represents advective flow and the capillary has no contribution in that shock. In summary my question is can I give this physical reason of the neglecting capillary pressure lead the low saturations to advance slow where we get triple saturation. I’m just trying to understand why do we have triple saturation or in another context why the fractional flow curve behave as it is when we neglect capillary pressure. With regards
@@hamzaalyaseri6047 The fractional flow as a function of saturation does ignore capillary forces. As I said previously, the inclusion of capillarity tends to smear out the shock. I do not understand what you mean by "triple saturation": the fractional flow is always a single-valued function of saturation.
@@BoffyBlunt thank you professor for your patience and fast response, i will change my question to : why the shape of Sw vs distance takes this shape, is there is any physical reason or its just math problem ?
@@hamzaalyaseri6047 It is always both - consistent with the maths and physically-sensible. Since the wavespeed for low water saturations is low, a shock develops. In reality this shock is smeared out by capillary forces, but there is a sharp change in water saturation at the leading edge of the water front.