Fracture Half-Length and Linear Flow in the South Belridge Diatomite.

Nott, D.C.; Hara, Shohei

doi:10.2118/21778-ms

Cited by 12 publications

(6 citation statements)

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“…5 is the isothermal pressure solution corresponding to water injection into 0.1 md (a P = 1.79Â10 -1 ft 2 /D) diatomite under the same reservoir conditions (Nott and Hara 1991). Comparison indicates that when steam is injected, pressure maintenance due to thermal expansion is as much as 1.8 times that of isothermal waterflooding over 10 times the dimensionless distance.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…To compensate for the low formation permeability, hydraulic fracturing has proved to be an effective technique for increasing steam injectivity and oil productivity in the diatomite (Nott and Hara 1991). However, the tight pattern spacing required to ensure economic performance (1¼-acre or less) makes hydraulic fracture orientation, morphology, and response to steam injection critical parameters in evaluating steamdrive viability.…”

Section: Introductionmentioning

confidence: 99%

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Imaging Fractures Using Temperature Transients From Perturbation Analysis—A Novel Surveillance Technique Applied to the Belridge Diatomite

Shahin

Johnston

2009

SPE Journal

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Results of a temperature transient analysis of data from Shell's diatomite steamdrive pilots are used to image hydraulic injection fracture lengths, angles, and heat injectivities into the low-permeability formation. The Phase I pilot is a limited-interval injection test. In Phase II, steam is injected into two 350-ft upper and lower zones through separate hydraulic fractures. Temperature response of both pilots is monitored with 16 logging-observation wells.A perturbation analysis of the nonlinear pressure diffusion and heat-transport equations indicates that at a permeability of approximately 0.1 md or less, heat transport in the diatomite tends to be dominated by thermal diffusivity, and pressure diffusion is dominated by the ratio of thermal expansion to fluid compressibility. Under these conditions, the temperature observed at a loggingobservation well is governed by a dimensionless quantity that depends on the perpendicular distance between the observation well and the hydraulic fracture divided by the square root of time. Using this dependence, a novel method is developed for imaging hydraulic-fracture geometry and relative heat injectivity from the temperature history of the pilot.The azimuth of the Phase I hydraulic fracture is determined to be 14 AE 2 N-NE. The azimuth of the Phase II upper hydraulic fracture is determined to be 16 AE 2 N-NE in the northern half of the pilot, and estimated to increase to 21 AE 2 in the southern half of the pilot. The azimuth of the lower hydraulic fracture averages 19 AE 4. The hydraulic fractures are found to be symmetric around both injectors, with an estimated length of 200 ft.Increased steam injection after the first year of pilot operations caused what is interpreted to be horizontal fractures toward the west in the G cycle and the east in the M cycle. These features are imaged to be at least 100 and 160 ft, respectively, along the hydraulic fracture azimuth.These conclusions are compared to tiltmeter data, microseismic data, and a simulation history match of pilot performance. Microseismic events recorded in the pilot are apparently not diagnostic of heat delivery to the formation.

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Section: Discussion Of Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Imaging Fractures Using Temperature Transients From Perturbation Analysis—A Novel Surveillance Technique Applied to the Belridge Diatomite

Shahin

Johnston

2009

SPE Journal

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“…Nott and Hara (1991) used producer 564N-29 as a field example of formation linear production behavior. The well is discussed here both to integrate primary linear flow behavior with the oil-cut function Y over a 10 year history and to describe a productivity change as a result of a refracture treatment.…”

Section: Flow Regime Field Examplesmentioning

confidence: 99%

“…On the basis of the analytical work by Cinco-Ley and Samaniego (1981) for pressure transient analysis (constant rate solution), the flow behavior follows the various linear flow models, depending on the fracture conductivity and storage capacity. For production data analysis (rate transient analysis with constant bottomhole pressure), Nott and Hara (1991) developed a formation linear flow formula for oil production rate by assuming infinite fracture conductivity. Azari et al (1991) developed production rate formulas for both bilinear and formation linear flow with finite fracture conductivity.…”

Section: Introductionmentioning

confidence: 99%

Production-Performance Diagnostics Using Field-Production Data and Analytical Models: Method and Case Study for the Hydraulically Fractured South Belridge Diatomite

Yang¹

2012

SPE Reservoir Evaluation &Amp; Engineering

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Oil and water production data are regularly measured in oilfield operations and vary from well to well and change with time. Theoretical models are often used to establish the production expectation for different recovery processes. A performance surveillance understanding can be developed by comparing the field production data with the production expectation. This comparison generates quantitative or qualitative signals to determine whether the producer meets production expectations or the producer is underperforming and appropriate operational action is required to address the underperformance.The case study is for the South Belridge diatomite in California. This hydraulically fractured diatomite reservoir is currently under waterflood and steamflood. A methodology is proposed to establish the production expectation from historical production data. For primary depletion, the formation linear and bilinear flow models are applied to producers with vertical hydraulic fractures. For waterflood, an analytical method derived from the Buckley-Leverett displacement theory is used. Those analytical methods can predict production and provide surveillance signals for producers in the primary and waterflood recovery stages. For steamflood, a semiquantitative performance/surveillance criterion is proposed on the basis of understanding the mechanistic oil banking concept and reservoir simulation results for steamflood and waterflood. With those models representing expected production performance, an integrated flow regime diagram is proposed for production surveillance. A performance expectation can be developed for an individual producer. A significant overperformance relative to the expectation normally indicates changes in the recovery mechanism or improvement in sweep efficiency. A significant underperformance usually signifies an operational issue that requires correction to optimize the production performance.In the case study, the surveillance methodology for producers under primary depletion, waterflood, or steamflood is demonstrated by use of historical production data. In addition, water channeling between injectors and producers and its impact on production performance are discussed. On the basis of this surveillance methodology, some operational actions were proposed, and successful results are demonstrated. Examples of forecast for an individual producer in the primary depletion stage and field scale prediction in the waterflood stage are provided. Application indicates that the proposed methodology can serve as a convenient and practical tool for reservoir surveillance and operational optimization.

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“…For these wells, there appears to be only linear flow during transient and outer boundary dominated flow. Actual field data shows long-term linear flow for years in a large number of wells [3][4][5][6][7][8][9][10][11][12] because of the extremely low permeability.…”

Section: Introductionmentioning

confidence: 99%

Production Analysis of Long-Term Linear Flow in Tight Gas Reservoirs: Case Histories

Arevalo-Villagran¹,

Wattenbarger²,

Fernando³

et al. 2001

Proceedings of SPE Annual Technical Conference and Exhibition

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractActual field data show linear flow in a large number of tight gas wells. Sometimes this linear flow is transient for years. Linear flow is normally associated with hydraulic fractures. Short-term linear flow production analysis may characterize fracture treatments, but long-term linear flow production may be controlled in some cases by the reservoir geometry; in others, it is controlled by the natural occurring reservoir properties. In this paper, long-term linear flow caused by both the presence of natural parallel fractures and vertical flow in a high permeability streak is investigated. An analytical matrixparallel fracture model for a single-phase flow is presented. A systematic procedure to analyze linear flow in tight gas wells is described. Application of this methodology to production analysis from several tight gas wells and validation of the results by using numerical simulation are also shown.

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Fracture Half-Length and Linear Flow in the South Belridge Diatomite.

Cited by 12 publications

References 0 publications

Imaging Fractures Using Temperature Transients From Perturbation Analysis—A Novel Surveillance Technique Applied to the Belridge Diatomite

Imaging Fractures Using Temperature Transients From Perturbation Analysis—A Novel Surveillance Technique Applied to the Belridge Diatomite

Production-Performance Diagnostics Using Field-Production Data and Analytical Models: Method and Case Study for the Hydraulically Fractured South Belridge Diatomite

Production Analysis of Long-Term Linear Flow in Tight Gas Reservoirs: Case Histories

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