Are we there yet?23 Sep 2024 05:24
People are getting twitchy because flow rates have not been released. The reasons for this are related to reservoir engineering. Not only is the person who is shrillest in their demands not a shareholder, but should understand the reasons better than most, since they claim to have an engineering background. As I have stressed previously, I am not an engineer, so what follows is probably a little simplistic, and quite possibly wrong.
Well pressure is pretty simple β you stick a pressure gauge on the wellhead and record the reading. But what is flow rate? Is it the volume of gas per unit of time with all the stops fully opened? There's a big clue in Methodology's Reddit magnum opus on Rharb Basin flow rates β every reading has an associated choke size. A choke is simply a valve, with its diameter given in 64ths of an inch β so a 32 choke is Β½β in diameter. Why use a choke to restrict flow? The purpose is to obtain the optimum, not maximum, rate. A number of bad things can happen if you let the gas blow at maximum pressure.
* You could seriously damage the gas collection & processing equipment downstream if it is not designed to withstand that pressure.
* If the speed of the gas flow is greater than the speed of sound in that medium, you will get a sustained sonic boom β you can imagine the effect on people and equipment.
* Unrestrained pressure release may damage the reservoir formation, blasting debris into the borehole.
*The reservoir adjacent to the borehole may deplete faster than gas can flow through the reservoir, leading to 'coning' β an empty or water-filled space with its apex at the wellbore.
What you need for engineering planning and commercial projections is 'flow assurance'. This takes into account characteristics of the various reservoirs downhole, together with their individual pressures β can they all be blended and used simultaneously? Do you isolate one or more and use them sequentially? What is the sand/dust/water content? Are there any ngls/condensates? What are the characteristics of the gas collection pipework, valves, pumps, compressors, etc? This is complex stuff, with the aim of achieving a sustainable flow rate β reasonably constant and predictable over time, a known rate of reservoir depletion, and a sound basis for commercial calculations.
What if you want 50mmcfgd, but the 4 holes you have only produce 10 each? You don't over-run them at 12.5, for the reasons above, you just drill another (onshore = cheap) well. This is part of the Field Development Plan.
If PRD is at this stage, clearly there is gas. The optimisation of the gas flow from downhole reservoir to processing plant will enable finalisation of either a gas sales agreement or a sale of the whole CNG business. For MOU-5 and G2P or G2EU, with or without helium, a similar process will need to be undertaken. Possibly also in T &T.
With regard to the CNG development, imo we are approaching endgame.