Georges, Saverio, Russ... your trial member has it wrong.
Coning (with one 'n'), by definition cannot take place in a fractured reservoir. Coning refers to the relatively uniform (in 3-D), or symmetrical if you like, drawing in of fluids (possibly water, in this case) around the open hole section of the wellbore.
This draw is created essentially by a partial vacuum, in turn created by the sudden evacuation of all this gas from pore-spaces in the reservoir. The water is drawn in to fill the lower-pressure area, in the shape of a cone. It would be in the shape of a sphere, but gravity comes into the equation.
If the reservoir was fractured, water migration would be referred to as "channeling".
I also disagree that water would be "pulled in from a couple of feet below". After flowing 1.5 billion cubic feet of gas (think about that number) and many thousand cubic feet of condensate, water finally came into the picture. That is a HUGE volume of hydrocarbons. If the water is, indeed, "coning" in from around the wellbore, it will have been drawn in from much further away (I would guess 100+ feet below the base of the wellbore). We would have seen water in the first 5 minutes of the blow-out if it was a couple of feet down.
Condensate, as the trial member states, is a light hydrocarbon liquid, but it is definitely much lighter than crude oil.
I am not that familiar with reservoir physical chemistry, but it seems to me that under those extreme pressures, gas is more likely to be a liquid at depth than the reverse.
The trial member's final analysis is also wrong.
They have assumed (like many people with a legitimate excuse for not understanding) that just because we have 17 feet of open hole below the casing, we must be only 17 feet into the formation ...WRONG.
The reason they set casing here is because they had been drilling for some time in the Temblor sand (I was told 300 feet) and suddenly experienced severe drilling problems. It was a safety issue that led to the decision to run casing at the point they did.
I believe we are closer to 317 feet into the sand, and thus 317 feet into the gas zone.
I do agree that we likely have a gas/condensate/oil/water situation. These fluids arrange themselves naturally in the rock in that order, gas being the least dense (lightest) and water the most dense (heaviest).
If we do have 317 feet of gas pay, then coning can be avoided in Bellvue #2 by producing the gas from higher up, and at a much lower rate (using a choke at the wellhead to restrict flow). This allows the reservoir to "relax" and maintain relative equilibrium - that is, keep the oil/water contact relatively flat, as it was naturally, before we stuck a big straw in the top!!!
Your trial member really should read what he writes before sending. The spelling is atrocious, the grammer terrible, and I wish he/she would call it the "Temblor Formation" and not the "tremblor".
Don't believe everything you read - they are trying to "baffle with bullshit!!!".
Regards,
Rick. |
