Interested in when a well might be fracked for a second time. Especially in the Bakken. Seems like there would be many variables deciding when and if it was worthwhile?
So far it's very rare, either it's a new well that something went wrong with and they never completed the amount of frack stages they first intended, I actually have one of those myself or a very early well that was completed in a single stage.
In the Bakken the completion of a well is the greatest expense, and it's a matter of where you get the greatest bang for the buck, do you spend the money to recomplete a well in an area that has already been depleted, or do you drill a well a few hundred yards away in an area that has not been seriously depleted? Remember if you recomplete the old well that is depleted, you likely won't be getting the flush production that gives the rapid payback that a new well in an area that still has good field pressure can give.
My well that was fracked twice had a pinched liner. 6 frack stages were completed and the well produced 13k barrels in the first year. After being repaired and an additional 8 frack stages completed the same well produced 14,800 barrels in 15 days. If I remember correctly that well was originally scheduled to have 24 frack stages just like the other three wells drilled from the same pad so I think of it more as a delayed completion rather than a refrack.
Marathon bought 4 wells that had been completed with a single frack stage and decided to recomplete them. The wells had produced poorly from first production so I doubt the field pressure was greatly reduced. Three of the four wells showed marked improvement of about 1/3 and the fourth showed no change. Those 3 marathon wells that showed improvement were still in my opinion mediocre after the refrack of 20 stages. This was I believe the best possible situation that would recommend a refrack. Had the wells been completed with even 10 frack stages, I don't believe the refracks would have happened, the wells would have produced significantly better and the field pressure would have been diminished. I have not looked at a well that had only 10 frack stages in quite awhile in the Bakken, most are 18 to 30 or more these days. Refracks in the Bakken are almost as rare as hens teeth.
If someone knows where there are dozens of Bakken wells that have been refracked, rather than some sort of delayed completion and or any refracks that have happened on Bakken wells with more than 10 frack stages, I wish someone would clue me in because I have not found more than those mentioned above. I hope this helps.
It is rare to re-frac a well, which RW mentioned. However, companies have been re-fracing in Louisiana and have increased production by 27%. With regard to the Bakken, Marathon oil has 2300 wells with 100 of them candidates for re-fracing. As RW mentioned, some of the older Bakken wells were single stage; now 30-35 stage fracing is common place, which is the case with Marathon.
So far, Marathon has re-fraced a few wells and the results have far exceeded their expectations, delivering returns that are large enough to merit additional investment (~$1M/well).
One thing to keep in mind, when it comes to fracing a well, current fracing companies in the Bakken are kept busy getting new wells on line, let alone re-fracing older wells. During the winter fracing slows way down due to the cold temperatures that affect fracing operations; sometimes as much as one-two months after well is drilled. Right now (during the summer) fracing takes place about 2 weeks after a well is drilled, if they catch up from winter operations.
Thank you both gentlemen. What does the say 30-35 stage fracing mean? How do they then determine how many frack stages? Thanks so much for the excellent information you all are so kind to share! God Bless, Randy
The fracks stages are done at intervals. The length of the wellbore stays the same so the more frack stages the closer they are together and the more the source rock is stimulated.
The engineering is interesting to me and I am sorry to say that I do not have time to discuss it at length but I will give one example. Many early wells in the Bakken were very water heavy, I believe because they were trying to crack the rock as far as they could and fracked into water zones. I think many of these wells showed improvement over time because fractures not well propped open with propant/sand will heal themselves in time because of the great pressures at those depths. From what I have been hearing EOG tries to frack closer to the wellbore with tighter intervals, more oil, less water that is costly to dispose of.