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Exploration and Production (E&P) Technology in the Upstream Oil and Gas Industry

Hydraulic frack designs in resource plays have been improving for years.  In the western USA, large structures with huge amounts of natural gas were identified decades ago.  However, the tightness of the formations, i.e. low permeability, prevented them from being commercially developed.  At one point nuclear fracs were proposed as a way of breaking up the formations so gas would flow.  And, in fact, three atomic fracks were performed:  Gasbuggy (outside Farmington, NM), Rusilon (outside Grand Valley, CO), and Rio Blanco (outside Rifle, CO).  The Pinedale/Jonah fields were not atomic frack sites,  and the industry struggled for decades to "crack the nut" of how to get the gas out.  Finally, in the mid-1990's, a Denver based independent started to experiment with massive hydraulic fracks as a way to unlock the vast quantities of gas contained in the deep, thick formations. After several years of modifications, the below is what one major operator detailed as its approach.


Wells are directionally drilled from pads on 10 acre spacing using s-shaped well paths; equipment used is a mud motor with a 1.5 degree bent sub.
Slim profile relative to other wells drilled to similar depths (958-in. surface casing, 7-in. intermediate casing, 4½-in. production casing)
Underbalanced, oil based muds systems are used along with PDC bits for more efficient drilling and increased ROP
Wells are drilled in batches from pads and perfed
Some operators are using natural gas powered drilling rigs to help address air quality concerns


Issues include
discontinuous, lenticular sands
maintaining zonal isolation during frac treatments
perforation interval selection
proppant selection and volume
understanding which zones are producing: every zone is production logged
Each frac runs 100-400 ft, and include 2-4 individual sands
Slick water and x-linked gel are pumped in the same frac at rates of 25-45 bbl/min
Each well is fraced with 15-22 frac stages, averaging 105,000  lb of proppant per stage
The proppant mix is 65% 20/40 Ottawa, and 35% intermediate ceramic
Lower intervals are fraced with X-linked systems and the upper intervals are fraced with slick water slurries