Borehole Breakouts and In-situ Rock Stress--A Review
Stephen Prensky, U.S. Geological Survey, Denver
[Originally Published in 1992, The Log Analyst, v. 33, no. 3, p. 304-312.]
Introduction
Borehole breakouts, so named by Babcock (1978), are enlargements and elongation of a borehole in a preferential direction and are formed by spalling of fragments of the wellbore in a direction parallel to the minimum (least) horizontal stress (Sh). Borehole spalling occurs along intersecting shear fractures generated soon during drilling and progresses with time (Bell, 1990). The identification and analysis of borehole breakouts as a technique for in-situ measurement of stress orientation and magnitude, and for identifying orientation (azimuth) of both naturally occurring and induced fractures (hydrofrac), has received a great deal of attention during the past ten years. Knowledge of the orientation of horizontal earth stresses derived from analysis of borehole breakouts is important to the following areas of study:
Reservoir Applications
Planning Hydrocarbon Exploration Strategies. Locating fracture porosity and permeability in specific rock formations to maximize recovery (Babcock, 1978; Schafer, 1979; Baumgardner and Laubach, 1987).
Developing Production Strategies and Reservoir Engineering. In contrast to breakouts, hydraulic (induced) fractures form perpendicular to the least principal stress. Knowledge of the orientation of borehole breakouts can be used for predicting hydraulic fracture propagation. This information is essential to (a) optimal placement of production and injector wells when designing and analyzing effective well stimulation, waterflooding, and enhanced oil recovery (EOR) programs, especially in fractured and/or low-permeability reservoirs (Hassan, 1982; Bell and Babcock, 1986; Hansen and Purcell, 1986; Guenot, 1989; Lacy and Smith, 1989).
Drilling and Wellbore Mechanics
Avoiding problems associated with drilling and borehole instability stemming from in-situ rock stress (Hottman et al., 1979; Maury and Sauzay, 1987).
Studies of Crustal Stress
The orientation of stress within a tectonic plate reflects the forces acting on that plate, e.g. extension, compression, or strike-slip (Gough et al., 1983; Suter, 1987; Dart and Zoback, 1988; Zoback et al., 1989; Zoback and Zoback, 1991). Stress data for many boreholes are used to examine regional stresses patterns and this information is in turn used to constrain plate tectonics models (Solomon et al., 1980; Mount and Suppe, 1987; Moos and Zoback, 1990; Harper and Szymanski, 1991; Zoback, 1991; Zoback and Magee, 1991), regional tectonic processes (such as volcanism and faulting), and potential seismic hazards in zones of crustal weakness (Zoback and Zoback, 1980; see discussion below).
Rock Mechanics
Understanding rock mechanics for the safe design and construction of cylindrical openings in stressed rock, e.g. tunnels, mine shafts, and caverns (for waste storage). Sidewall failure (or slabbing), similar to borehole breakouts, occurs often, and on a large scale during these projects (Kaiser et al., 1985; Ewy and Cook, 1990a, 1990b).
Background
The advent of the four-arm dipmeter with its opposed pairs of calipers permitted a more accurate description and measurement of borehole shape than the earlier three-arm version, specifically, borehole asymmetry or ellipticity. Leeman (1964) reported fracturing of the borehole wall in zones of high stress and Cox (1970), in a study in Alberta, Canada, was the first to observe a preferential elongation of borehole direction, and he further observed that this elongation direction was independent of geologic age and the magnitude of dip. Babcock (1978) also noted that depth, lithology, hole deviation, and breakout azimuth are independent elements; that breakouts are associated with a slowing or cessation of dipmeter-tool rotation since the calipers lock into a preferred azimuth (Figure 1); and that the azimuths of borehole elongation and jointing in outcrop are parallel. While noting that the minimum tectonic stress direction is parallel to the dominant azimuth of borehole elongation, Babcock (1978) and Schafer (1979), ascribed breakouts to the intersection of the borehole with preexisting joints (as seen in outcrop).
One of the early selling points for Schlumberger's Fracture Identification Log, based on the 4-arm dipmeter, was that breakouts (hole ellipticity), particularly in the fractured chalks of Louisiana and south Texas, could be caused by fracturing, and breakouts could be used as an indicator of fracturing in these rocks (Beck et al., 1977; Babcock, 1978; Schafer, 1979). Cox (1982) did not find a correlation between fractures and breakouts except for the Cotton Valley and Austin Chalk. Baumgardner and Laubach (1987) suggested that the same borehole elongation in the Travis Peak Formation of east Texas may be caused by fractures and Baumgartner et al. (1989) found breakouts associated with natural fractures in crystalline rock.
Bell and Gough (1979, 1982) noted that the conclusions of Babcock (1978) and Schafer (1979) regarding breakouts and jointing did not account for a second, equally prominent and perpendicular joint set also seen in outcrop. They argued that breakouts are related to unequal horizontal stresses. Hottman et al. (1979) independently arrived at the same conclusion.
Breakouts as a Stress Indicator
Drilling a wellbore in stressed rock causes these stresses to be redistributed and a zone of yielded rock, a breakout, results (Maloney and Kaiser, 1989). Bell and Gough (1979, 1981, 1982) and Gough and Bell (1981, 1982) using data from in-situ stress measurements demonstrated that breakouts both in Canada and Texas are formed by brittle shear fracture around the borehole and that breakout azimuth is related to the compressive forces of unequal horizontal principal stresses near the borehole (Figure 2). Breakouts form in the direction perpendicular to the principle horizontal compressive stress. In addition to conclusions based on empirical observation, formation of borehole breakouts has been analyzed based on rock mechanics theory (Bell and Gough, 1982; Gough and Bell, 1982; Zoback et al., 1985; Papanastasiou et al., 1989; Plumb, 1989; Zheng et al., 1989; Qian and Pedersen, 1991; Fjaer et al., 1992) and laboratory experiments (Mastin, 1984; Haimson and Herrick, 1985, 1986, 1989; Ewy et al., 1990; Onaisi et al., 1990; Hansen, 1991).
McGarr and Gay (1978), Zoback and Zoback (1980), Zoback and Haimson (1982), and Gough and Gough (1987) reviewed the available methods used for in-situ measurement of stress: overcoring (stress-relief), induced hydrofracturing (microfracturing), strain/stress gauge, earthquake fault-plane solutions. Stress orientations inferred from breakout azimuths are consistent with data obtained by these other, independent measurements of in-situ stress (Blumling et al., 1983; Fordjor et al., 1983; Newmark, et al., 1984; Dart, 1985; Hickman et al., 1985; Plumb and Hickman, 1985; Teufel, 1985; Zoback et al., 1985; Bell and Babcock, 1986; Plumb and Cox, 1987; Mount, 1989).
Identifying Breakouts
Not all elliptical borehole enlargements are stress-induced breakouts: Dart and Zoback (1988) described six types of borehole enlargement, including breakouts; Fordjor et al. (1983), Plumb and Hickman (1985), and Springer (1987) proposed criteria for recognizing breakouts from 4-arm dipmeter logs and distinguishing them from other causes of borehole ellipticity (Figure 3). Plumb and Cox (1987) discussed four assumptions involved in inferring stress directions from dipmeter data: (1) failure and elongation of the borehole is due to brittle fracture and not to plastic deformation; (2) elongation is not due to the intersection of natural fractures; (3) the well is drilled parallel to one of the principal stresses; (4) borehole elongation is symmetric.
Besides the dipmeter several other downhole devices have been used for examining borehole breakouts; these include motion pictures (Springer and Thorpe, 1981; Springer et al., 1984) and both acoustic (BHTV) and electrical (FMS) borehole-imaging devices (Healy et al., 1984; Newmark et al., 1984; Paillet and Kim, 1985; Plumb and Hickman, 1985; Zoback et al., 1985; Barton, 1988; Barton et al., 1988; Burns, 1988; Shamir et al., 1988; Morin et al., 1989; Shamir and Zoback, 1989) (Figure 4). While dipmeter data are most often used in regional and field studies because they are widely available in areas of hydrocarbon exploration, imaging tools are considered the best devices for identifying breakouts and distinguishing them from other types of borehole elongation (Springer, 1987; Bell, 1990). Plumb (1989) used digital BHTV data for establishing criteria to distinguish breakouts caused by natural fractures versus drilling-induced fractures.
Measurements of Stress Magnitudes from Breakouts
The reliability of hydraulic fracturing for measurement of in-situ stress in the hostile environments of high pressure and high temperature (deep wells, geothermal wells, naturally fractured rock) is questionable and an alternate method for estimating stress magnitudes is needed, i.e., the quantitative analysis of breakouts (Haimson and Herrick, 1986; Zoback et al., 1986). Theoretical and laboratory studies conclude that in quasi-isotropic (e.g., sedimentary) rocks, breakout geometry (depth and width, shape) are related to the magnitude of Sh. Haimson (1987) declareed that the potential exists for using breakouts to estimate stress magnitudes if the dimensions of the failed zone can be determined. Barton et al. (1988) proposed a method for using breakout width, obtained from BHTV images, to estimate stress magnitudes. There is, however, disagreement as to the extent to which this geometry can be used and Bell (1990) pointed out the difficulty in obtaining reliable measurements needed to arrive at these values and as well as the need to better understand the mechanism of rock failure. Vernik and Zoback (1992) reported that Shmax profiles estimated from breakouts compares "fairly well" with those from hydraulic fracturing. Additional work is being carried out to better understand implications for in-situ stress evaluation from breakouts in anisotropic (e.g., igneous and metamorphic) rocks where the failure mechanism may not be the same as in isotropic rocks (Paillet and Kim, 1985; Plumb, 1989; Vernik and Zoback, 1989, 1990).
Recent Developments
Mastin (1988) discussed the effect of borehole deviation on breakouts in different faulting regimes (normal, strike-slip, thrust). Lacy and Smith (1989), Avasthi et al. (1990), and Bell (1990) reviewed the methods used for measuring in-situ stress and fracture orientation, including breakout data, and the applications of this information to well stimulation. Allison and Nielson (1988) suggested an additional application of breakout data: to guide directional drilling in geothermal wells to increase the probability of intersecting the greatest number of active or open fractures. A primary objective of deep scientific drilling is the determination of in-situ stress; however, the high pressures required to initiate induced fractures for measuring in-situ stress, combined with the high bottomhole temperatures encountered in theses wells, may exceed limits of current packer technology (Zoback et al., 1986). Thus, borehole breakouts may become the primary method for evaluating in-situ stress orientation.
Regional Stress Regimes
The unequal stresses around a borehole are representative of regional stress fields that are related to compressional, extensional, and strike-slip tectonic forces that produce regional faulting. An improved understanding of the orientation and magnitude of earth stress, in part obtained through analysis of borehole breakouts, can contribute to understanding earthquake mechanisms and future prediction/control (McGarr and Gay, 1978; Zoback and Zoback, 1980; Zoback and Zoback, 1981; Newmark et al., 1984; Zoback and Healy, 1984; Springer, 1987; Zoback et al., 1987; Shamir et al., 1988; Zoback, 1991; Vernik and Zoback, 1992; Zoback and Healy, 1992). Under normal conditions, breakout orientation is constant (homogeneous) with depth. In seismically active areas, where the stress regime has been disturbed by faulting, breakout orientations are heterogeneous and this heterogeneity may serve as an indicator of geologically recent fault movement (Nielson, 1989; Allison, 1990; Shamir et al., 1990; Hansen, 1991, Zoback and Magee, 1991).
Recent studies of regional stress regimes and stress provinces that incorporate data from borehole breakouts include: global patterns (Zoback et al., 1989); the Western Canada basin (Bell and Babcock, 1986; Gough and Gough, 1987; Bell, 1990); central and eastern U.S. (Dart and Zoback, 1987); Oklahoma and Texas Panhandle (Dart, 1989); California (Mount, 1989); Continental U.S. and North America (Zoback and Zoback, 1989; 1991); Alaska (Estabrook and Jacob (1991); Canada (Adams and Bell, 1991; Yassir and Dusseault, 1991); Mexico and Central America (Suter, 1987; 1991); Europe (Becker et al., 1987; Brereton and Evans, 1989; Brereton and Mueller, 1991; Muller et al., 1992); United Kingdom (Evans and Brereton, 1990); North Sea and Norwegian shelf (Clauss et al., 1989; Spann et al., 1991).
Summary
Measurement of in-situ rock stress is important to hydrocarbon exploration and exploitation, rock mechanics, and scientific research. Data on borehole breakouts acquired by dipmeter and, more recently, from borehole-imaging tools, provide a readily available, inexpensive, and worldwide database for the determination of in-stress orientation. Ongoing research on the physics of breakout formation under different stress conditions may eventually permit determination of in-situ stress magnitude directly from breakout geometry.
References
Adams, J., and Bell, J.S., 1991, Crustal stress in Canada, chapter 20, in Slemmons, D.B., Engdahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Geological Society of America, Decade Map Volume 1, p. 367-386.
Allison, M.L., 1990, Remote detection of active faults using borehole breakouts in the Heber geothermal field, Imperial Valley, California: Geothermal Resources Council Transactions, v. 14, part 2, p. 1359-1364.
Allison M.L., and Nielson, D.L., 1988, Application of borehole breakouts to geothermal exploration and development; an example from Cove Fort-Sulphurdale, Utah: Geothermal Resources Council Transactions, v. 12, p. 213-219.
Avasthi, J.M., Nolen-Hoeksema, R.C., El Rabaa, A.W.M., and Wilson, L.E., 1990, In-situ stress evaluation in the McElroy field, west Texas, SPE-20105, in SPE Permian Basin Oil and Gas Recovery Conference Proceedings: Society of Petroleum Engineers, p. 189-196. Later published in 1991: SPE Formation Evaluation, v. 6, no. 3, p. 301-309.
Babcock, E.A., 1978, Measurement of subsurface fractures from dipmeter logs: AAPG Bulletin, v. 62, no. 7, p. 1111-1126. Reprinted in 1990, in Foster, N.H., and Beaumont, E.A., eds., Formation evaluation II--log interpretation: AAPG Treatise of Petroleum Geology Reprint Series No. 17, p. 457-472.
Barton, C.A., 1988, Development of in-situ stress measurement techniques for deep drillholes: Stanford University, unpublished Ph.D. dissertation, 192 p.
Barton, C.A., Zoback, M.D., and Burns, K.L., 1988, In-situ stress orientation and magnitude at the Fenton geothermal site, New Mexico, determined from wellbore breakouts: Geophysical Research Letters, v. 15, no. 5, p. 467-470.
Baumgardner, R.W., Jr., and Laubach, S.E., 1987, Analysis of natural fractures and borehole ellipticity, Travis Peak Formation, east Texas: Gas Research Institute, Report GRI 87-0211, 128 p. Also published as, Wellbore ellipticity in east Texas--in-situ stress or fracture-related spalling [abs.]: EOS, Transactions, American Geophysical Union, v. 68, no. 44, November 3, p. 1460.
Baumgartner, J., Rummel, F., Haimson, B.C., and Lee, M.Y., 1989, In situ stress measurements and natural fracture logging in drill hole CY-4, the Troodos ophiolite, Cyprus, in Gibson, I.L., Malpas, J., Robinson, P.T., and Xenophontos, C. eds., Cyprus crustal study project; initial report, hole CY-4: Geological Survey of Canada, Paper 88-9, p. 315-330.
Beck, J., Schultz, A., and Fitzgerald, D., 1977, Reservoir evaluation of fractured Cretaceous carbonates in south Texas, paper M, in 18th Annual Logging Symposium Transactions: Society of Professional Well Log Analysts, 25 p.
Becker, A., Blumling, P., and Muller, W.H., 1987, Recent stress field and neotectonics in the eastern Jura Mountains, Switzerland: Tectonophysics, v. 135, p. 277-288.
Bell, J.S., 1990, Investigating stress regimes in sedimentary basins using information from oil industry wireline logs and drilling records, in Hurst, A., Lovell, M.A., and Morton, A.C., eds, Geological applications of wireline logs: Geological Society of London Special Publication No. 48, p. 305-325.
Bell, J.S., and Babcock, E.A., 1986, The stress regime of the Western Canadian Basin and implications for hydrocarbon production: Bulletin of Canadian Petroleum Geology, v. 34, no. 3, p. 364-378.
Bell, J.S., and Gough, D.I., 1979, Northeast-southwest compressive stress in Alberta--Evidence from oil wells: Earth and Planetary Science Letters, v. 45, p. 475-482.
Bell, J.S., and Gough, D.I., 1981, Intraplate stress orientations from Alberta oil-wells, in O'Connell, R.J., and Fyfe, W.S., eds., Evolution of the Earth: American Geophysical Union, Geodynamics Series, v. 5, p. 96-104.
Bell, J.S., and Gough, D.I., 1982, The use of borehole breakouts in the study of crustal stress, in M.D. Zoback and B.C. Haimson, eds., Workshop on hydraulic fracturing stress measurements [December 2-5], proceedings: U.S. Geological Survey Open-file Report 82-1075, p. 539-557. Also published in 1983, as Hydraulic fracturing and stress measurements: National Academy Press, p. 201-209.
Blumling, P., Fuchs, K., and Schneider, T., 1983, Orientation of the stress field from breakouts in a crystalline well in a seismic active area: Physics of the Earth and Planetary Interiors, v. 33, p. 250-254.
Brereton, N.R., and Evans, C.J., 1989, Rock stress orientations from borehole breakouts, in Louwrier, K., Staroste, E., Garnish, J.D., and Karkoulias, eds., European geothermal update [4th international seminar on the results of the EC geothermal energy research and demonstration, Florence, Italy, 27-30, proceedings]: Kluwer Academic Publishers, Dordrecht, p. 213-231.
Brereton, R., and Mueller, B., 1991, European stress--contributions from borehole breakouts: Philosophical Transactions Royal Society London, Series A, v. 337, no. 1645, p. 165-179.
Brown, R.O., 1978, Application of fracture identification logs in the Cretaceous of north Louisiana and Mississippi: Gulf Coast Association of Geological Societies Transactions, v. 28, p. 75-91.
Burns, K.L., 1988, Televiewer measurement of the orientation of in situ stress at the Fenton Hill hot dry rock site, New Mexico: Los Alamos National Laboratory Report LA-UR-88-1775, 6 p. Also published in 1988, Geothermal Resources Council Transactions, v. 12, p. 229-235.
Clauss, B., Marquart, G., and Fuchs, K., 1989, Stress orientations in the North Sea and Fennoscandia, a comparison to the central European stress field, in Gregersen, S., and Basham, P.W., eds., Earthquakes at North-Atlantic passive margins--neotectonics and postglacial rebound: Kluwer Academic Publishers, Dordrecht, p. 277-287.
Cox, J.W., 1970, The High Resolution Dipmeter reveals dip-related borehole and formation characteristics, paper D, in 11th Annual Logging Symposium Transactions: Society of Professional Well Log Analysts, 26 p.
Cox, J.W., 1982, Long-axis orientation in elongated boreholes: The Technical Review, v. 30, no. 3, December, p. 15-25. Also published in 1983, as paper J, in 24th Annual Logging Symposium Transactions: Society of Professional Well Log Analysts, 17 p.
Dart, R., 1985, Horizontal-stress directions in the Denver and Illinois basins from the orientations of borehole breakouts: U.S. Geological Survey Open-File Report 85-733, 41 p.
Dart, R.D., 1989, Horizontal stresses from well-bore breakouts and lithologies associated with their formation, Oklahoma and Texas Panhandle, in Johnson, K.S., ed., Anadarko Basin Symposium, 1988: Oklahoma Geological Survey Circular No. 90, p. 97-120. Later published in 1990 as, In Situ Stress Analysis of Wellbore Breakouts from Oklahoma and the Texas Panhandle: U.S. Geological Survey Bulletin 1866-F, 28 p.
Dart, R.D., and Zoback, M.L., 1988, Well-bore breakout-stress analysis within the continental United States, paper L, in 2nd International Symposium on Borehole Geophysics for Minerals, Geotechnical, and Groundwater Applications [Golden, Colorado, October 6-8, 1987], proceedings: Society of Professional Well Log Analysts, Minerals and Geotechnical Logging Society Chapter-at-Large, p. 139-149. Later published in 1989 as, Wellbore breakout stress analysis within the central and eastern continental United States: The Log Analyst, v. 30, no. 1, January-February, p. 12-24.
Estabrook, C.H., and Jacob, K.H., 1991, Stress indicators in Alaska, chapter 21, in Slemmons, D.B., Engdahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Geological Society of America, Decade Map Volume 1, p. 387-399.
Evans, C.J., and Brereton, N.R., 1990, In situ crustal stress in the United Kingdom from borehole breakouts, in Hurst, A., Lovell, M.A., and Morton, A.C., eds., Geological applications of wireline logs: Geological Society of London Special Publication No. 48, p. 327-338.
Ewy, R.T., and Cook, N.G.W., 1990a, Deformation and fracture around cylindrical openings in rock--I; observations and analysis of deformations: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, v. 27, no. 5, p. 387-407.
Ewy, R.T., and Cook, N.G.W., 1990b, Deformation and fracture around cylindrical openings in rock--II; initiation, growth, and interaction of fractures: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, v. 27, no. 5, p. 409-427.
Ewy, R.T., Myer, L.R., and Cook, N.G.W., 1990, Investigation of stress-induced borehole enlargement mechanisms by a liquid metal saturation technique, SPE-21519: Society of Petroleum Engineers, unsolicited paper, 32 p.
Fjaer, E., Holt, R.M., Horsrud, P., and Raaen, A.M., 1992, Stress around boreholes, and borehole failure criteria, chapter 4, in Petroleum related rock mechanics: Elsevier, Amsterdam, Developments in Petroleum Science, No. 33, p. 109-134.
Fordjor, C.K., Bell, J.S., and Gough, D.I., 1983, Breakouts in Alberta and stress in the North American plate: Canadian Journal of Earth Science, v. 20, p. 1445-1455
Gough, D.I., and Bell, J.S., 1981, Stress orientations from oil-well fractures in Alberta and Texas: Canadian Journal of Earth Sciences, v. 18, p. 638-645.
Gough, D.I., and Bell, J.S., 1982, Stress orientations from borehole fractures with examples from Colorado, east Texas, and northern Canada: Canadian Journal of Earth Sciences, v. 19, no. 7, p. 1358-1370.
Gough, D.I., Fordjor, C.K., and Bell, J.S., 1983, A stress province boundary and tractions on the North American plate: Nature, v. 305, October 13, p. 619-621.
Gough, D.I., and Gough, W.I., 1987, Stress near the surface of the earth: Annual Review of Earth and Planetary Sciences, v. 15, p. 545-66.
Guenot, A., 1989, Borehole breakouts and stress fields: International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts, v. 26, no. 3/4, p. 185-195.
Haimson, B.C., 1987, Measurement of in-situ stress, chapter 17, in Sammis, C.G., and Henyey, T.L., eds., Geophysics--field measurements: Academic Press, Inc., Orlando, Methods of Experimental Physics, v. 24, part B, p. 377-408.
Haimson, B.C., and Herrick, C.G., 1985, In situ stress evaluation from borehole breakouts, experimental studies, in E. Ashworth, ed., Research and engineering applications in rock masses [26th U.S. symposium on rock mechanics, South Dakota School of Mines and Technology, Rapid City, 26-28 June, proceedings], volume 2: A.A. Balkema, Boston, p. 1207-1218.
Haimson, B.C., and Herrick, C.G., 1986, Borehole breakouts--A new tool for estimating in situ stress, in Stephansson, O., ed., Rock stress and rock stress measurements [international symposium on rock stress and rock stress measurements [Stockholm, September 1-3], proceedings]: Centek Publishers, Stockholm, p. 271-280.
Haimson, B.C., and Herrick, C.G., 1989, Borehole breakouts and in situ stress, in Rowley, J.C., ed., Drilling symposium 1989 [12th annual energy-sources technology conference and exhibition, Houston, January 22-25): American Society of Mechanical Engineers, New York, PD-Vol. 22, p. 17-22.
Hansen, K.S., 1991, Comparison between field observations and theory for stress-induced borehole ellipticity, in Roegiers, J-C., ed., Rock mechanics as a multidisciplinary science; proceedings of the 32nd U.S. symposium: A.A. Balkema, Rotterdam, p. 995-1004.
Hansen, K.S., and Purcell, W.R., 1986, Earth stress measurements in the South Belridge oil field, Kern County, California, SPE-15641: Society of Petroleum Engineers, 61st annual meeting [New Orleans] preprint, 15 p. Later published in 1989, SPE Formation Evaluation, v. 3, no. 4, December, p. 541-549.
Harper, T.R., and Szymanski, J.S., 1991, The nature and determination of stress in the accessible lithosphere: Philosophical Transactions Royal Society London, Series A, v. 337, no. 1645, p. 5-24.
Hassan, D., 1982, A method for predicting hydraulic fracture azimuth and the implications thereof to improve hydrocarbon recovery, paper 82-33-19: Petroleum Society of CIM [Canadian Institute of Mining and Metallurgy], presented at 33rd Annual Technical Meeting, preprint, 12 p.
Healy, J.H., Hickman, S.H., Zoback, M.D., and Ellis, W.L., 1984, Report on televiewer log and stress measurements in core hole USW-G1, Nevada Test Site, December 13-22, 1981: U.S. Geological Survey Open-File Report 84-15, 47 p.
Hickman, S.H., Healy, J.H., and Zoback, M.D., 1985, In situ stress, natural fracture distribution and borehole elongation in the Auburn geothermal well, Auburn, New York: Journal of Geophysical Research, v. 90, no. B7, p. 5497-5512.
Hottman, C.E., Smith, J.H., and Purcell, W.R., 1979, Relationship among earth stresses, pore pressure, and drilling problems offshore Gulf of Alaska, SPE-7501: Journal of Petroleum Technology, v. 31, no. 11, p. 1477-1484.
Kaiser, P.K., Guenot, A., and Morgenstern, N.R., 1985, Deformation of small tunnels, part IV--behavior during failure: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, v. 22, no. 3, p. 141-152.
Lacy, L.L., and Smith, M.B., 1989, Fracture azimuth and geometry determination, chapter 16, in Gidley, J.L., Holditch, S.A., Nierode, D.E., and Veatch, R.W., Jr., eds., Recent advances in hydraulic fracturing: Society of Petroleum Engineers, Monograph Series No. 12, p. 341-356.
Leeman, E.R., 1964, The measurement of stress in rock, part I, the principles of rock stress measurements; part II, borehole rock stress measuring instruments: Journal of the South African Institute of Mining and Metallurgy, v. 65, no. 2, p. 45-114.
Maloney, S., and Kaiser, P.K., 1989, Results of borehole breakout simulation tests, in Maury, V., and Fourmaintraux, D., eds., Rock at great depth: A.A. Balkema, Rotterdam, , v. 2, p. 745-752.
Mastin, L.G., 1984, Development of borehole breakouts in sandstone: Stanford University, unpublished M.S. thesis, 101 p.
Mastin, L., 1988, Effect of borehole deviation on breakout orientations: Journal of Geophysical Research, v. 93, no. B8, p. 9187-9195.
Maury, V.M., and Sauzay J-M., 1987, Borehole instability; case histories, rock mechanics approach, and results, SPE/IADC-16051, in SPE/IADC Drilling Conference Proceedings: Society of Petroleum Engineers, p. 11-24.
McGarr, A.M., and Gay, N.C., 1978, State of stress in the Earth's crust: Annual Review of Earth and Planetary Sciences, v. 6, p. 405-436.
Moos, D., and Zoback, M.D., 1990, Utilization of observations of well bore failure to constrain the orientation and magnitude of crustal stresses--Application to continental, Deep Sea Drilling Project, and Ocean Drilling Program boreholes: Journal of Geophysical Research, v. 95, no. B6, June 10, p. 9305-9325.
Morin, R.H., Anderson, R.N., and Barton, C., 1989, Analysis and interpretation of the borehole televiewer log; information on the state of stress and the lithostratigraphy at hole 504B, chapter 10, in Mazzullo, E.K., ed., Proceedings of the Ocean Drilling Program, v. 111, scientific results: Texas A & M University, Ocean Drilling Program, p. 109-118.
Mount, V.S., 1989, Present-day stress directions in California, chapter 2, in State of stress in California and a seismic structural analysis of the Perdido fold belt, northwest Gulf of Mexico: Princeton University unpublished Ph.D. dissertation, p. 20-56.
Mount, V.S., and Suppe, J., 1987, State of stress near the San Andreas fault--implications for wrench tectonics: Geology, v. 15, no. 12, p. 1143-1146.
Muller, B., et al., 1992, Regional patterns of stress in Europe: Journal of Geophysical Research, v. 97, no. B7, June 10, [in press].
Newmark, R.L., Zoback, M.D., and Anderson, R.N., 1984, Orientation of in situ stresses in the oceanic crust: Nature, v. 311, October 4, p. 424-429. Also published in 1985, as, Orientation of the in situ stresses near the Coast Rica rift and Peru-Chile trench--Deep Sea Drilling Project Hole 504B, in Initial reports of the Deep Sea Drilling Project, v. 83: U.S. Government Printing Office, p. 511-515.
Nielson, D.L., 1989, Stress in geothermal systems: Geothermal Resources Council Transactions, v. 13, p. 271-276.
Onaisi, A., Sarda, J.P., and Bouteca, M., 1990, Experimental and theoretical investigation of borehole breakouts, in Hustrulid, W.A., and Johnson, G.A., eds., Rock mechanics contributions and challenges [proceedings of the 31st U.S. symposium on rock mechanics]: A.A. Balkema, Rotterdam, p. 703-710.
Paillet, F.L., and Kim, K., 1985, The character and distribution of borehole breakouts and their relationship to in situ stresses in deep Columbia River basalts: Rockwell Hanford, Richland, Washington, Operations Report RHO-BW-CR-155, December, 27 p. Later published in 1987, Journal of Geophysical Research, v. 92, no. B7, p. 6,223-6,234. Later reprinted in 1990, in Borehole imaging reprint volume: Society of Professional Well Log Analysts, p. 387-398.
Papanastasiou, Vardoulakis, I.G., and Santarelli, F.J., 1989, Modeling borehole breakouts, in Rowley, J.C., ed., Drilling symposium 1989: American Society of Mechanical Engineers, PD-Vol. 22, p. 49-55.
Plumb, R.A., 1989, Fracture patterns associated with incipient wellbore breakouts, in Maury, V., and Fourmaintraux, D., eds., Rock at great depth: A.A. Balkema, Rotterdam, v. 2, p. 761-768.
Plumb, R.A., and Cox, J.W., 1987, Stress directions in eastern North America determined to 4.5 km from borehole elongation measurements: Journal of Geophysical Research, v. 92, no. B6, May 10, p. 4805-4816.
Plumb, R.A., and Hickman, S.H., 1985, Stress-induced borehole elongation--A comparison between the four-arm dipmeter and the borehole televiewer in the Auburn geothermal well: Journal of Geophysical Research, v. 90, no. B7, p. 5513-5521.
Qian, W., and Pedersen, L.B., 1991, Inversion of borehole breakout orientation data: Journal of Geophysical Research, v. 96, B12, November 10, p. 20,091-20,107.
Schafer, J.N., 1979, A practical method of well evaluation and acreage development for the naturally fractured Austin Chalk formation, paper U, in 20th Annual Logging Symposium Transactions: Society of Professional Well Log Analysts, 25 p. Later published in 1980, The Log Analyst, v. 21, no. 1, January-February, p. 10-23.
Shamir, G., and Zoback, M.D., 1989, Detailed analysis of wellbore breakouts in the Cajon Pass scientific drillhole, in Rowley, J.C., ed., Drilling symposium 1989 [12th annual energy-sources technology conference and exhibition, Houston, January 22-25): American Society of Mechanical Engineers, New York, PD-Vol. 22, p. 11-15. A similar paper was published in 1989 as, The stress orientation profile in the Cajon Pass, California, scientific drillhole, based on detailed analysis of stress induced borehole breakouts, in Maury, V., and Fourmaintraux, D., eds., Rock at great depth: A.A. Balkema, Rotterdam, p. 1041-1048. An expanded version was published later in 1992, as Stress orientation profile to 3.5 km depth near the San Andreas Fault at Cajon Pass, California: Journal of Geophysical Research, v. 97, no. B4, p. 5059-5080.
Shamir, G., Zoback, M.D., and Barton, C.A., 1988, In situ stress orientation near the San Andreas fault--Preliminary results to 2.1 km depth from the Cajon Pass scientific drillhole: Geophysical Research Letters, v. 15, no. 9, supplement, p. 989-992.
Shamir, G., Zoback, M.D., and Cornet, F.H., 1990, Fracture-induced stress heterogeneity--Examples from the Cajon Pass scientific drillhole near the San Andreas fault, California, in Barton, N., and Stephansson, O., eds., Rock joints [international symposium on rock joints, June 4-6, 1990, Loen Norway, proceedings]: A.A. Balkema, Rotterdam, The Netherlands, p. 719-724.
Solomon, S.E., Richardson, R.M., and Bergman, E.A., 1980, Tectonic stress--models and magnitudes: Journal of Geophysical Research, v. 85, B11, p. 6086-6092.
Spann, H., Brudy, M., and Fuchs, K., 1991, Stress evaluation in offshore regions of Norway: Terra Nova, v. 3, no. 2, p. 148-152.
Springer, J.E., 1987, Stress orientations from well bore breakouts in the Coalinga region: Tectonics, v. 6, no. 5, p. 667-676.
Springer, J.E., and Thorpe, R.K., 1981, Borehole elongation versus in-situ stress orientation: Lawrence Livermore National Laboratory, Report No. UCRL-87018, 15 p.
Springer, J.E., and Thorpe, R.K., and McKague, H.L., 1984, Borehole elongation and its relation to tectonic stress at the Nevada Test Site: Lawrence Livermore National Laboratory, Report No. UCRL-53528, 43 p.
Suter, M., 1987, Orientational data on the state of stress in northeastern Mexico as inferred from stress-induced borehole elongations: Journal of Geophysical Research, v. 92, no. B3, p. 2,617-2,626.
Suter, M., 1991, State of stress and active deformation in Mexico and western Central America, chapter 22, in Slemmons, D.B., Engdahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Geological Society of America, Decade Map Volume 1, p. 401-421.
Teufel, L.W., 1985, Insights into the relationship between wellbore breakouts, natural fractures, and in situ stress, in E. Ashworth, ed., Research and engineering applications in rock masses [26th U.S. symposium on rock mechanics, South Dakota School of Mines and Technology, Rapid City, 26-28 June, proceedings]: Boston, A.A. Balkema, v. 2, p. 1199-1206.
Vernik, L., and Zoback, M.D., 1989, Effects of rock elastic and strength properties in estimation of the state of stress at depth, in Maury, V., and Fourmaintraux, eds., Rock at great depth: A.A. Balkema, Rotterdam, v. 3, p. 1041-1048.
Vernik, L., and Zoback, M.D., 1990, Strength anisotropy in crystalline rock--implications for assessment of in situ stresses from wellbore breakouts, in Hustrulid, W.A., and Johnson, G.A., eds., Rock mechanics contributions and challenges [31st U.S. symposium on rock mechanics, proceedings]: A.A. Balkema, Rotterdam, p. 841-848.
Vernik, L., and Zoback, M.D., 1992, Estimation of maximum principal stress magnitude from stress-induced well bore breakouts in the Cajon Pass scientific research borehole: Journal of Geophysical Research, v. 97, no. B4, April 10, p. 5109-5119.
Yassir, N.A., and Dusseault, M.B., 1991, Stress trajectories in southwestern Ontario using wellbore breakout orientations, in Roegiers, J-C., ed., Rock mechanics as a multidisciplinary science [32nd U.S. Symposium on rock mechanics, proceedings]: A.A. Balkema, Rotterdam, p. 83-92.
Zheng, Z, Kemeny, J., and Cook, N.G.W., 1989, Analysis of borehole breakouts: Journal of Geophysical Research, v. 94B, no. 6, June 10, p. 7,171-7,182.
Zoback, M.D., 1991, State of stress and crustal deformation along weak transform faults: Philosophical Transactions Royal Society London, Series A, v. 337, no. 1645, p. 141-150.
Zoback, M.D., and Haimson, B.C., eds, Workshop on Hydraulic Fracturing Stress Measurements, proceedings: U.S. Geological Survey Open-file Report 82-1075, p. 539-557. Also published in 1983, Hydraulic fracturing and stress measurements: National Academy Press, 270 p.
Zoback, M.D., and Healy, J.H., 1984, Friction, faulting and in situ stress: Annales Geophysicae, v. 2, no. 6, p. 689-698.
Zoback, M.D., and Healy, J.H., 1992, In situ stress measurements to 3.5 km depth in the Cajon Pass scientific research borehole--implications for the mechanics of crustal faulting: Journal of Geophysical Research, v. 97, no. B4, April 10, p. 5039-5057.
Zoback, M.D., Mastin, L., and Barton, C., 1986, In-situ stress measurements in deep boreholes using hydraulic fracturing, wellbore breakouts, and Stoneley-wave polarization, in Stephansson, O., ed., Rock stress and rock stress measurements [international symposium on rock stress and rock stress measurements (Stockholm, September 1-3), proceedings]: Cenek Publishers, p. 289-299.
Zoback, M.D., Moos, D., Mastin, L., and Anderson, R.N., 1985, Well bore breakouts and in situ stress: Journal of Geophysical Research, v. 90, no. B7, p. 5523-5530.
Zoback, M.D., and Zoback, M.L., 1981, State of stress and intraplate earthquakes in the United States: Science, v. 213, July 3, p. 96-104.
Zoback, M.D., and Zoback, M.L., 1991, Tectonic stress field of North America and relative plate motions, chapter 19, in Slemmons, D.B., Engdahl, E.R., Zoback, M.D., and Blackwell, D.D., eds., Neotectonics of North America: Geological Society of America, Decade Map Volume 1, p. 339-366.
Zoback, M.D., Zoback, M.L., Mount, V.S., et al., 1987, New evidence on the state of stress of the San Andreas fault system: Science, v. 238, November 20, p. 1105-1111.
Zoback, M.L., and Magee, M., 1991, Stress magnitudes in the crust--constraints from stress orientation and relative magnitude data: Philosophical Transactions Royal Society London, Series A, v. 337, no. 1645, p. 181-194.
Zoback, M.L., and Zoback, M., 1980, State of stress in the conterminous United States: Journal of Geophysical Research, v. 85, no. B11, November 10, p. 6113-6156.
Zoback M.L., and Zoback, M.D., 1989, Tectonic stress field of the continental United States, chapter 24, in Paiser, L.C., and Mooney, W.D., eds., Geophysical Framework of the Continental United States: Geological Society of America, Memoir 172, p. 523-539.
Zoback, M.L., Zoback, M.D., Adams, J., et al., 1989, Global patterns of tectonic stress: Nature, v. 341, September 28, p. 291-298.
About the Author
Stephen Prensky is a research geologist with the U.S. Geological Survey, Branch of Petroleum Geology, Denver, Colorado. He has been with the USGS since 1975, working as well-log specialist in reservoir characterization. Previous experience includes exploration and production geology with Texaco's Offshore Division. He holds a B.A. and M.S. in geology from SUNY Binghamton, and the University of Southern California. Stephen has been a member of SPWLA since 1978, and is currently serving on the Board of Directors as Vice-President of Publications. His "Bibliography of Well-Log Applications," has been published annually in The Log Analyst since 1987. Stephen is also a member of AAPG, MGLS, SCA, and SPE.
Figure Captions
Figure 1. Annotated dipmeter log record with zones of borehole breakout. Breakout intervals are indicated by caliper trace separation and interruption in the normal diagonal pattern of the azimuthal trace. Fluctuation in conductivity values also delineate, to some extent, breakout intervals (Figure and caption from Dart and Zoback, 1988).
Figure 2. Cross-sectional schematics of wellbores showing original borehole shape (dashed line) and enlarged borehole shape (solid line). Orientation of borehole elongation relative to the directions of the principal horizontal stresses for breakout (A) and fracture (B) is shown (Figure and caption from Dart and Zoback, 1988).
Figure 3. Examples of dipmeter caliper logs and common interpretations of the borehole geometry. Cal 1-3 and cal 2-4 indicate borehole diameter as measured between opposing dipmeter arms. (a) An in-gauge hole. (b) The geometry resulting from stress-induced wellbore breakouts. (c) A minor "washout" with superimposed elongations. (d) A key seat where the sonde is not centered in borehole resulting in one caliper reading being less than bit size. The shaded regions in the direction of elongation represent local zones of slightly higher conductivity when compared with orthogonal direction (figure and caption from Plumb and Hickman, 1985. Copyright by AGU, reprinted by permission).
Figure 4. Examples of borehole breakouts seen in borehole televiewer images. (a) and (b) are continuous and (c) discontinuous breakouts (from Paillet and Kim, 1987. Copyright by AGU, reprinted by permission).