Preliminary Stress Measurements in Central California Using the Hydraulic Fracturing Technique

Zoback, Mark D.; Healy, J. H.; Roller, John C.

doi:10.1007/978-3-0348-5745-1_9

Cited by 9 publications

(11 citation statements)

References 7 publications

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“…To examine the state of stress at depth, hydraulic fracturing stress measurements were made at various depths in each well. The techniques used in the tests as well as the interpretative methods used are similar to those previously described by Zoback et al [1977 and are only outlined below.…”

Section: Stress Measurementsmentioning

confidence: 79%

“…Although in many cases this assumption is clearly not valid and S H cannot be determined [cf. Zoback et al, 1977], this is not considered to be a problem in this study because the measurements were made in crystalline rock and in sections of the boreholes without detectable preexisting fractures and joints. the pressure at which the already formed fracture opened at the well bore to accept fluid on the third pressurization cycle and set T = 0 in (1) to compute SH.…”

Section: Methodsmentioning

confidence: 99%

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In situ study of the physical mechanisms controlling induced seismicity at Monticello Reservoir, South Carolina

Zoback¹,

Hickman²

1982

J. Geophys. Res.

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127

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In two --•l.l-km-deep wells, the magnitudes of the principal in situ stresses, pore pressure, permeability, and the distribution of faults, fractures, and joints were measured directly in the hypocentral zones of earthquakes induced by impoundment of Monticello Reservoir, South Carolina. Analysis of these data suggests that the earthquakes were caused by an increase in subsurface pore pressure sufficiently large to trigger reverse-type fault motion on preexisting fault planes in a zone of relatively large shear stresses near the surface. The measurements indicated (1) near-critical stress differences for reverse-type fault motion at depths less than 200-300 m, (2) possibly increased pore pressure at depth relative to preimpoundment conditions, (3) the existence of fault planes in situ with orientations similar to those determined from composite focal plane mechanisms, and (4) in situ hydraulic diffusivities that agree well with the size of the seismically active area and time over which fluid flow would be expected to migrate into the zone of seismicity. Our physical model of the seismicity suggests that infrequent future earthquakes will occur at Monticello Reservoir as a result of eventual pore fluid diffusion into isolated zones of low permeability. Future seismic activity at Monticello Reservoir is expected to be limited in magnitude by the small dimensions of the seismogenic zones.

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Section: Stress Measurementsmentioning

confidence: 79%

Section: Methodsmentioning

confidence: 99%

In situ study of the physical mechanisms controlling induced seismicity at Monticello Reservoir, South Carolina

Zoback¹,

Hickman²

1982

J. Geophys. Res.

Self Cite

127

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“…The hydrofrac technique was described in detail by Haimson and Fairhurst [1970] and interpretation of hydrofrac data was discussed at length by M.D. Zoback et al [1977Zoback et al [ , 1980b 1. In regions where more than one type of stress indicator was available a good correspondence exists between the results of the different methods, generally well within the estimated accuracy of individual determinations.…”

Section: In Situ Stress Measurementsmentioning

confidence: 99%

State of stress in the conterminous United States

Zoback¹,

Zoback²

1980

J. Geophys. Res.

833

383

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Inferring principal stress directions from geologic data, focal mechanisms, and in situ stress measurements, we have prepared a map of principal horizontal stress orientations for the conterminous United States. Stress provinces with linear dimensions which range between 100 and 2000 km were defined on the basis of the directions and relative magnitude of principal stresses. Within a given province, stress orientations appear quite uniform (usually within the estimated range of accuracy of the different methods used to determine stress). Available data on the transition in stress direction between the different stress provinces indicate that these transitions can be abrupt, occurring over <75 km in places. In the western United States, a region of active tectonism characterized by high levels of seismicity and generally high heat flow, the stress pattern is complex, but numerous stress provinces can be well delineated.

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“…For then there exists the possibility that the least horizontal stress may exceed the vertical stress by an arbitrary amount and thereby have induced the fracture to turn from vertical to horizontal as it propagated from the well bore[Warren and Smith, 1985], resulting in an ISIP that reflects the vertical stress[Zoback et al, 1977]. Note the difference in pumping pressures even though the intervals are only 10 m apart (seeFigure 4).…”

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confidence: 99%

Appalachian Stress Study: 1. A detailed description of in situ stress variations in Devonian shales of the Appalachian Plateau

1989

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We describe an experiment to measure variations in the state of stress within a horizontally bedded Devonian shale/sandstone/limestone sequence in western New York. A total of 75 stress measurements were made in three wells a kilometer or so apart using a wireline‐supported hydraulic‐fracturing system. The stress profiles indicate that a major drop in horizontal stress level occurs in the generally massive shales. This drop occurs principally across the lowermost member of a group of sand beds and corresponds to an offset in Sh and SH of 3.5 and 9 MPa, respectively. Above the sands, “thrust” regime conditions prevail, although the amount by which Sh exceeds Sv is undetermined since instantaneous shut‐in pressures (ISIPs) were clipped at the level of Sv due to fracture rotation. Below the sands, the regime is strike slip with both horizontal stresses showing lateral uniformity despite substantial variations in topography. The magnitude of Sh in the sand beds themselves and a lower limestone remains at least as great as Sv despite the decline in shale stress. Hence stress contrasts between these beds and neighboring shales become pronounced with depth. The contrast in Sh and SH between the lowermost sand and the immediately underlying shale is at least 6 and 14.5 MPa, respectively. SH levels in the lower strike‐slip regime are about 1.75 times greater than Sh and are less than the value required to initiate slippage on favourably oriented frictional interfaces. For the upper thrust regime and the sand and limestone beds, however, the inferred lower bound on SH is close to the slippage threshold for a Coulomb friction coefficient of 0.6. The orientation of SH is ENE with a standard deviation of 20°. Fracture traces were usually splayed, occasionally spanning 30° of well bore. No systematic correlation between mean orientation and lithology is evident. Significantly different orientations were obtained for adjacent tests in which almost identical ISlPs were observed, suggesting that the fractures quickly reorient themselves to propagate normal to the least principal stress direction. Similarly, vertical traces were observed in those tests where ISIPs apparently reflect Sv, suggesting that rotation to horizontal was rapid.

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Preliminary Stress Measurements in Central California Using the Hydraulic Fracturing Technique

Cited by 9 publications

References 7 publications

In situ study of the physical mechanisms controlling induced seismicity at Monticello Reservoir, South Carolina

In situ study of the physical mechanisms controlling induced seismicity at Monticello Reservoir, South Carolina

State of stress in the conterminous United States

Appalachian Stress Study: 1. A detailed description of in situ stress variations in Devonian shales of the Appalachian Plateau

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