Predicting The Effects of Pressure Decline
It can't be done with any degree of accuracy; its not a one-off event in the life cycle of a tight oil well located in an over-drilled sweet spot. We can see that in the rate of well productivity decline for new wells, in accelerating terminal decline rates for older wells and increasing water to oil ratios in all wells.
Above is a Novi Cumulative Oil vs. Time chart for all 2016-July 2025 Permian wells, all benches, normalized for lateral lengths.
2023 wells at month 19 have a cumprod. that is 3% lower than the average for the data set. 2024 wells are a course to be lower, and 2025 wells even lower. Can I be any clearer on this?
Pressure depletion is significant enough now in the Midland Basin that predicting EURs is fruitless. Same with Bone Springs wells in Lea County, for instance in EOG's over-drilled, horizontally and vertically communicated mess. EOG is fleeing to the Middle East and, of all places, Ohio, for a reason.
As my astute PE friend says from the IB; 'if you are not drilling Permian tight oil wells today, you are missing the boat. Tomorrow you will have lower IP60s, that decline incrementally faster, and make....way less money.'
Novi has an AI thing that can imply EURs from cumprods. but does not say its sophisticated enough to adjust those EURS for certain areas and specific benches as it suggests it should, below:
Again, cumprods. at specific times are NOT EURs and should not be used to imply EURs, not given the current extent of pressure depletion (in the Permian). Most everybody now accepts discounted estimates from type curves. I mean, there are 56,000 of the damn things...everywhere.
Above, pressure decline never stops. Along with that oil, gas, gas liquids, everything declines, except, generally speaking, WOR.
Gassier tight oil wells do not translate to higher associated gas cumprods. at given times and not ultimately higher recoveries. Pressure depletion is solution gas drive rock negatively affects associated gas production and above, even tight oil wells that are classified as "gas wells" because of high initial GOR. Above, 2024 and 2025 well gas productivity is falling.
After 15 years in the Permian we've got a good handle on gas recovery. 2.2 to 2.5 BCF associated gas for tight oil wells and 5.0 to 5.5 BCF for gas wells in Culberson and Western Eddy (before degradation effects); its pretty safe to say those will just decline as time goes by.
A fun little reminder about the New Mexico part of the Permian HZ play: once you study the depositional environment of the Bone Spring correlative interval in Lea County, the deepest part of the entire Delaware Basin, you begin to understand why it is so prolific. It is a very friable, brittle shaley-carbonate that has clean sand lenses embedded in it that can have up to 25-30% porosity. Once poor permeability can be improved with frac'ing there are benches within the Bone Springs that are awesome and numerous wells within Lea County have cumprods to date of 1.4 plus MM BO. A few I know of over 2 MM BO.
When EOG landed in Lea County in circ. 2018, it found shale heaven
Over half the wells drilled in the entire Delaware Basin are Bone Springs wells and EOG literally operates about 25% of those...in Lea County.
If you wanted to grow up and be in the tight oil business you would want to be in Lea County drilling 3 mile laterals...in the Bone Spring. It and Eddy County are about the only places left you can actually squeak out a living below $60, particularly with the new Trump BBB that reduced RI on BLM land back to 1/8th.
Wells cost more ($11MM) because they are deeper and more expensive to operate (the Bone Springs makes the Gulf of Mexico in produced water every year.
So why is Lea County rolling over headed down with all that good juicy Bone Springs?
It is packed full of HZ Bone Springs wells, stuffed, that communicate with each other both horizontally and vertically and because of the unique characteristics of the Bone Springs and wells that drain much bigger areas, it is pressure depleted, badly, IMO. Go back to Figure 1, the correlative interval is not very thick with less than 500 feet separating benches that were drilled, mostly by EOG, on too close a spacing and gutted with no regard for pressure maintenance.
There are not very many Tier 3 and 4 level locations in Lea County, mostly sub-standard benches that won't produce like the Bone Springs and Lea County will drop pretty quickly, I think. If you are looking to Lea County, New Mexico for associated gas as AI and/or LNG feedstock, I don't know where you will drill the wells and put the produced water.
In nine years Lea County's associated gas from a well declines to 150 MCFPD and is still declining 15% per year (Novi).