"Slick Water Fracturing and Small Proppant" The future of stimulation or a slippery slope?

Abstract

Abstract Over the past 10 years Ely Corp has supervised more than 100,000 "Slick Water Fracture treatments". After more than 30 years of dominance by extremely viscous crosslinked gels, viscous oils, emulsions and foams, the industry has in selection of fracturing fluids, moved to the point that the vast majority of fracturing fluids are either water and friction reducer or combinations of linear gel and or crosslinked gel that is very rapidly degraded to water once in the formation. In a similar time frame our industry has moved rapidly away from specific selection criteria of proppant based on strength under closure and conductivity profiles which were enhanced by both size, particle distribution, and inherent strength. The dominate proppants now used in the industry are smaller proppant such as 40/70 and 70/140 (100 mesh). The switch to thin fluids was mainly because of intense efforts from individuals such as George Mitchell and other innovative companies who steadfastly believed in the potential of producing from virtually impermeable matrix source rock and were open to try any available technology. The switch to small proppant was driven in most cases by the lack of transport capability of the thin fluids, and in many cases due to lack of available higher strength proppant. The success of these slick water frac fluids has, in our opinion, been due to creating a drastically different geometry combined with much larger volumes. The type of frac fluids described have been present in the history certainly since the 50's but not with comparable rate and volume and typically not with the dominate proppant being 40/70 or smaller. The paper will, utilizing our data base and public production data, illustrate what has truly changed the dynamic of fracturing in our industry. We will also illustrate techniques to optimize slick water fracs based on a combination of new generation technology and experience in not only source rock shale but many so called conventional reservoirs which have only now become economical with use of high volume slick water treatments where more conventional viscous fluids failed. Based on the broad success of these fluids, we will propose a hypothesis for why these fluids and proppants, which defy conventional frac theory, have made the industry more closely evaluate even the most basic frac theories that we have followed for multiple decades.