Morning Rick,
If we are splitting "greyhairs" when we discuss physics, fluid flow, phase behavior and thermodynamics, what are we splitting when we critique spelling and grammar, Rick ?? If we split many more, I won't have any left to split!! <ggg>
1: If gravity were not an issue, then fluids drawn in at the "end of the straw" would indeed do so in a more or less spherical manner.
We're talking about fluid flow through porous media, Rick. The conical shape of the water cone derives from pressure gradients in the reservoir and the fact that the water is below (how far we don't know, but perhaps "a few hundred feet") the wellbore. Many other factors- porosity, permeability, anisotropy, fluid densities, etc. influence the shape and the rate of development of the cone. Gravity has a very minor influence on the cone, but even in the absence of gravity, could the cone be spherical?? Of course not.
2: If those fluids around the wellbore were not allowed to move to the "area of lower relative pressure" left behind, what do you suppose would occupy those pore-spaces?
But that's exactly what happens, Rick. I did not comment otherwise.
3: Yes, I did state the 18,000 psi. The "experts" have already stated that the pressure is in excess of 15,000 psi. Don't ask for a reference, I can't remember where I read that, but I'm sure someone else has read it too.
If your "experts" happen to be close to the actual operations and are referencing a measured pressure then great, it is probably at least ballpark accurate (Wow!!!). But, you have cautioned us in a recent post not to believe everything that we read and you are correct in doing so. I do know that I have seen (on this thread I believe) a calculation that purported to prove that the pressure had to be approaching 18,000 psi because the well was some 17,600 feet deep, it was flowing water, and because "water density is 1" the pressure had to be about 18,000 psi . Well, if this is the "expert" you happen to be relying upon when you state an 18,000 psi pressure, then you are being misled. A column of fresh water would exert a maximum bottomhole pressure of only about 7,650 psia. (Although the relative density of fresh water is 1, the pressure gradient within water is only 0.43333 psi/ft). A slightly saline water column would add only a modest amount to that. And, gasification of the column would of course reduce the reservoir pressure required to "flow" water from the well.
Of course, given the geology of the play, the reservoir pressure can be overpressured relative to hydrostatic pressures. But, do we know for sure what the pressure actually is? Can we rely upon the 18,000 psi, Rick?? Or, do we still only know what the joint venture was anticipating, 15,000 psi ?? If the experts were expecting 15,000 psi but actually found 18,000 psi you will of course appreciate that there could be some reason to be concerned!!!
If the water "flooded" the open hole section, then how can we still be producing the same amount of gas and condensate as we were before the water appeared? That doesn't make sense to me.
We aren't, Rick. The moment that the water production began, the production rate of the other fluids decreased. It is a physical impossibility to continue producing the same amount of gas, condensate and oil as was being produced prior to the appearance of water (irrespective of the water source).
But, it is true that introduction of water at a shallow depth should impede hydrocarbon production less than if the same amount of water were produced from total depth.
Both cases for the source of the water are valid, given current info.
Of course they are both possible. That's why Boots & Coots can not rule out either one yet.
..is this well well behaved, or badly behaved?
The problem child grew increasingly problematic each day but now it is becoming more submissive. <ggg>
You are assuming that the casing failed from day 1.
No, not at all. I do believe that to be the case (i.e. that the production casing\cement bond was incompetent at the time of the blowout) but I do not require an assumption of casing failure to rely upon water coning as being the source of the water production.
Of course, I have NO evidence\data, but I do suspect that poor cement bond in fact contributed to the blowout in the first place. But we could debate that for several weeks and not get anywhere, so....
Those doglegs are perfect candidates for casing erosion.
I am glad that you understood my explanation of the "sandblaster" phenomenon so well!!! However, in addition to just cutting the casing, several other conditions need be met in order for uphole water entry at the location of the "cut" to be plausible. Possible?? For sure. Probable?? Who can know without the technical data specific to this well. But, it is a lot lower probability than is the straight "coning" phenomenon. You will recall that Boots & Coots do not consider it at all surprising that water has appeared. To them it's just kinda normal. They understand coning phenomenon. But, with several lives at risk, they MUST always be aware that there could be alternate explanations for the water, and they must plan accordingly.
I think you might find that if Boots and Coots managed to choke back the fluid being produced at the surface, enough to pressure up the wellbore a little, then the water production could tail off, assuming it is coming from uphole.
If they are able to choke it back, the production of all fluids will tail off, at least initially. But, a reduction in the water rate would not allow an exclusive conclusion as to the source of the water, shallow or bottomhole, because the water cut would decline in both cases.
This pressure differential, combined with a venturi effect can account for the volume of water we are seeing at the surface, and it would not interfere with HC production at the basal open hole.
Venturi effect ?? That's funny, Rick. <gg>
The laws of physics are such that the introduction of any water into this wellbore, no matter from where, will adversely impact the HC production at the basal open hole. Sorry, but that's just the way it is.
I sure don't know everything either, Rick. Golly, I wish I did. (I wouldn't have to spend so much time learning if that was the case!!!) I honestly mean NO malice in my "critique" of your posts, Rick. But, I have always enjoyed the engineer/geologist rivalry and will not hesitate to take my little digs. I trust that you will too now that I've admitted to being "one of those". Seriously Rick, I do only undertake to better understand and clarify some of the facts surrounding the mystery that is East Lost Hills #1. Hopefully, if you are prepared to discuss my questions, we can each enhance our understanding of this reservoir. You have provided a lot of valued information to this thread and no doubt most of it is quite accurate. It would be a shame if your credible information were discounted simply because "exuberant reporting" makes other info appear less credible.
Rick, I admit to needing a "refresher" course in Geology 202 and will likely enroll in the next one that you offer. In the meantime, do you happen to know if the gas being produced is from the upthrown or the downthrown Temblor block? Also, I recall reading elsewhere that the operator lost the mud system at some point during drilling operations on this well. Do you know at what depth? Did they lose the mud to the Temblor (and that is what triggerred the blowout)? Or, was that why they ran the casing a bit early?
I appreciate any info you can provide on these questions.
I touted it as a big winner back then and still stand by my words.
Most of us sure hope you are right!!! I for one share your belief that this is a large discovery. Unfortunately, it is likely going to be a long time until we actually know how large.
Later,
grayhairs |
