Numerical modeling of massive hydraulic fractures. First annual report, September 1980-August 1981

Technical Report · Fri Apr 01 04:00:00 EST 1983

OSTI ID:6237261

Palmer, I D

Models of 3D fracture propagation are being developed to study the effect of variations of stress and rock properties on fracture shape and bottomhole pressure. Initially a blanket sand bounded by higher stress zones is considered, with stress and rock property contrasts symmetric about the payzone axis, and the fracture criterion is assumed to be K/sub i/ = K/sub c/, where K/sub i/ is stress intensity factor, and K/sub c/ the fracture toughness. First, quasi-static models are considered briefly, because they give information on fracture behavior in the limit that (..mu..g) ..-->.. 0. Second, viscous fluid flow effects have been considered in two different models, FL1 and FL2. Flow is along the payzone only, and leakoff is neglected. The net pressure at the tip, a, of the long axis required by the boundary condition K/sub i/ = K/sub c/ does not seem to be crucial in determining fracture height or bottomhole pressure. A parametric study has been conducted on effects of S/sub 2/-S/sub 1/, K/sub c/, and Young's modulus, E, on fracture shape and bottomhole pressure. It appears that K/sub c/ does not have as much effect as either E or S/sub 2/-S/sub 1/. Third, Model FL2, which represents better the vertical stress variation, shows the onset of a rapid growth in fracture height as S/sub 2/-S/sub 1/ is reduced. The onset of this divergence may be able to be used to give an upper or safe limit on the pumping parameters (..mu..q) to ensure good containment, although the behavior is dependent on the form of the fluid flow equation used, and this must await confirmation. Fourth, when the stress contrast is too low, or if a fracture breaks ghrough a containing zone, or in a lenticular gas sand, the fracture length/height ratio may be so low that both a better width equation and a better fluid flow equation, which includes azimuthal flows, need to be incorporated. 13 figures, 4 tables.

• Research Organization: Oral Roberts Univ., Tulsa, OK (USA)
• DOE Contract Number: AS19-80BC10215
• OSTI ID: 6237261
• Report Number(s): DOE/BC/10215-23; ON: DE83009168
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300 -- Petroleum-- Drilling & Production
03 NATURAL GAS
030900 -- Natural Gas-- Artificial Stimulation
Plowshare-- (-1989)
58 GEOSCIENCES
580300* -- Mineralogy
Petrology
& Rock Mechanics-- (-1989)
CRACK PROPAGATION
FAILURES
FLUID FLOW
FRACTURES
HYDRAULIC FRACTURES
MATHEMATICAL MODELS
MECHANICS
PARAMETRIC ANALYSIS
RESERVOIR PRESSURE
ROCK MECHANICS
STRESSES
WELL PRESSURE