The emergence of unconventional resource activity due to improvements in horizontal drilling techniques in the last 15 years has seen, literally, a seismic shift in U.S. hydrocarbon production and reserves growth as the methodology has extended its application to more and more geologic plays across the U.S. In 2013, horizontal wells account for more than 60% of all wells drilled in the U.S. However, the rate of success in economic wells has not kept pace with the burgeoning production. As more wells are drilled, the realization has come that these so-called shale plays are, in fact, highly heterogeneous in their nature and drilling wells on regular spacing does not guarantee the anticipated well economics. Without a detailed understanding of the lateral variability in reservoir quality of the formation, locations with the highest producibility potential may not be fully exploited. This paper discusses the complementary role that systematically designed and executed 3D seismic programs can play in providing the required information to describe the lateral rock property variations across the play. When integrated with downhole and production data, the knowledge on reservoir quality variations can be incorporated into the well planning and design process to most effectively exploit the play.
From the efforts in the Barnett Shale in the 1990's, the horizontal drilling techniques to economically tap the hydrocarbons locked in low permeability plays emerged. In the 2000's the technique proved its potential in plays such as the Haynesville and Marcellus with horizontal drilling and associated hydraulic fracturing releasing abundant gas and liquid hydrocarbons and extending its application to plays across the U.S. (Figure 1).
Horizontal drilling went from less than 10% of all wells drilled in 2004 to over 60% in 2013. The success of these techniques is most vividly demonstrated by the abundance of gas produced that rapidly exceeded the demand with the resultant impact on price. Today, the emphasis in the unconventional play arena is on liquids as demonstrated by the fact that, in 2013, over 75% of wells are addressing liquids (Figure 2)