Predicting the Orientation of Hydraulically Created Fractures in the Cotton Valley Formation of East Texas

Abstract

The tight gas sandstones of the Cotton Valley Forma· tion of East Texas require massive hydraulic fracture treatments to achieve economic rates of production. Engineering data indicate a well will efficiemly draill a maximum of 160 acres. Optimization of well spacing will require a knowl. edge of induced fracture orientation. At the presetlt time there is no reliable method u.;hereby this orientation can be measured.Oriented caliper data obtained from dipmeter logs run in fifty wells were used to investigate the borehole geometry through the Cotton Valley sandstones. It was found that quite often the sandstones when drilled through would "spall" or "wash-out" and that the borehole would be elliptical in shape with the major axis always oriented in a NW/SE direction. The opinion of the authors is that the consistency itl orientation is due to in-situ stresses within the rock, and a prediction can be made that hydraulically induced fractures in the Cotton Valley sandstones of East Texas will be oriented in a NW/SE direction.Primed in USA.

Orientation of In Situ Stresses near the Costa Rica Rift and Peru-Chile Trench: Deep Sea Drilling Project Hole 504B

“…These intervals are called "breakouts" in the petroleum industry when the short dimension is equal to the drill bit size (Babcock, 1978). Breakouts exhibiting well-grouped azimuths have been reported in several parts of North America (Cox, 1970;Babcock, 1978;Schafer, 1980;Brown et al, 1980;Bell, 1981, 1982;Springer and Thorpe, 1981;Gough, 1979, 1982;Plumb, 1982; Healy et al, pers. comm.…”

Evaluation Procedures in the Carboniferous of Northern Europe

“…Another mechanism for borehole elongation is postulated by Babcock 1978 andBrown 1980 in which borehole elongations are aligned with pre-existing natural fracture system.…”

Orientation of In Situ Stresses in the Pacific Plate: Deep Sea Drilling Project Hole 597C

“…Stress-induced wellbore breakouts form at an azimuth perpendicular to the maximum horizontal principal stress direction . A number of authors have described wellbore breakouts and reported their occurrence in wells from several parts of North America (Cox, 1970;Babcock, 1978;Schafer, 1980;Brown et al, 1980;Bell, 1981 and1982;Springer and Thorpe, 1981;Gough, 1979 and1982;Plumb, 1982;Hickman et al, 1982;Seeburger and Zoback, 1982;Gough et al, 1983;Fordjor et al, 1983) and in the oceanic crust (Zoback and Anderson, 1982;Newmark et al, 1984Newmark et al, , 1985. They have also reported problems in properly identifying these breakouts (e.g., Blumling et al, 1983).…”