"Water Flooding" In The Bakken -- June 7, 2020

I forget when, but within the past year, I suppose, a reader started noting something strange about the water that returned to the surface in the first few months after a well was fracked.

Example: these two wells were both completed in December, 2019, and both were completed in the same oil field, the Sanish. It may or may not be important to note that one well was completed in the middle Bakken, the other in the Three Forks. I think it may be relevant.

Look at the amount of water returned after the wells were fracked.

In the first well, as much as 84,000 bbls in one month (the 3-day return of 9,510 bbls extrapolates to 95,100 bbls of water over thirty days) was returned.

Now look at the amount of water regurgitated in the second well in the same period of time right after the well was fracked.

First, this well:

• 36754, 1,322, Kraken, Candace 15-22 1TFH

Pool	Date	Days	BBLS Oil	Runs	BBLS Water	MCF Prod	MCF Sold	Vent/Flare
BAKKEN	4-2020	30	26735	26815	49447	0	0	0
BAKKEN	3-2020	31	29954	30416	84028	29415	13105	15939
BAKKEN	2-2020	11	3305	2784	40380	3398	2278	983
BAKKEN	1-2020	3	3895	4048	9510	3972	3172	756
BAKKEN	12-2019	30	33569	33263	300	33570	15760	17382

Second, this well:

• 36130, A, Whiting, Harvey TTT 41-4HU, Sanish, t--; cum 137K in five months:

Pool	Date	Days	BBLS Oil	Runs	BBLS Water	MCF Prod	MCF Sold	Vent/Flare
BAKKEN	4-2020	30	26995	26968	3861	27947	27889	26
BAKKEN	3-2020	31	27511	27499	7364	22333	22093	210
BAKKEN	2-2020	29	29643	29677	9038	20518	19188	1303
BAKKEN	1-2020	31	31093	30998	8779	25914	6718	19165
BAKKEN	12-2019	21	21326	21148	11028	13332	0	13308

I may be seeing something that doesn't exist or reading more into it than the phenomenon deserves, but the amount of water being regurgitated among different wells is certainly fascinating. It has to be by design.

A reader commented on this:

Regarding 'novel water flood' in recent  wells ...

This is a brief rundown with what may be happening ...

1. One principal -- tied to Extreme Limited Entry perforations -- isolates individual stages that have rock which will 'open up' the pre-existing fissures within a range of pressure, say 1,500 psi. 

Another stage may have rock that will 'open up' at 1,000 psi. 

Another at, say, 2,000 psi.

These stages may vary from 120 feet in length to 350 feet, but the KEY component will be the point at which the needed pressure opens up the fissures. This characteristic is determined by several methods of measurement while drilling, along with years of experience.

2. The skillful use of 'far field' diverters temporarily blocks the horizontal spread of the fracturing. 

NOW, the operators are maintaining an 'open up' pressure in a 500 foot half length (from each side of the wellbore) while NOT having unwanted growth into the adjacent well's drainage.

Incorporating ultra tiny microproppants enhances the scouring/opening in this precise region of rock. This is where all that extra proppant has been going.

3. Final principle -- due to newest High Viscosity Friction Reducers (which do not damage formation when left 'in the ground' for many months) -- the artificially elevated formation pressure (akin to your 'water sweep'observation) now drives the oil which has come out of the rock (incredibly vast 'spider webby' fractures are now possible with aforementioned techniques) and produce high/very high oil production for many months.

4. Throw in the near ubiquitous use of gas-lift Artificial Lift, and this may explain some of the very high numbers from Continental, Kraken, Marathon, and others.

Most of the above is informed speculation, but it is probably a fairly accurate description of what is taking place.

I replied to the reader that I have a gut feeling of what is going on in the Bakken -- involving these "new" principles as well as additional factors -- but cannot articulate it as well as the reader does, and I certainly don't have the background or access to journal articles or papers which might support some of my thoughts. But literally reporting the IP and cumulative production of every well that comes off the confidential list, day in and day out, certainly gives one a feeling of the improvements that are being made.