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Oil and water production data are regularly measured in oil field 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 if the producer meets production expectation or if 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 based on Buckley-Leveret 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 semi-quantitative performance surveillance criterion is proposed based on 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 the purpose of production surveillance. A performance expectation can be developed for an individual producer. A significant over-performance relative to the expectation normally indicates changes in the recovery mechanism or improvement in sweep efficiency. A significant under-performance usually signifies an operational issue that requires correction in order to optimize the production performance. In the case study, the surveillance methodology for producers under primary depletion, waterflood, steamflood are demonstrated using historical production data. In addition, water channeling between injectors and producers and its impact on production performance is discussed. Based on this surveillance methodology, some operational actions were proposed and successful results are demonstrated. Examples of forecast for individual producer in primary depletion stage and field scale prediction in waterflood stage are provided. Application indicates that the proposed methodology can serve as a convenient and practical tool for reservoir surveillance and operational optimization. Copyright 2012, Society of Petroleum Engineers. Source


Albornoz F.,Aera Energy LLC
Society of Petroleum Engineers Western Regional Meeting 2012 | Year: 2012

A key to effective reservoir characterization lies primarily in obtaining good estimates of permeability. Permeability estimation through the integration of core, wireline and well test data has gained significant attention in recent years. However, these efforts are masked by vague implementation processes arising from calibration and scaling issues. This paper presents a systematic and unique approach for estimating permeability from the integration of core, wireline and pressure transient analysis data and prudently demonstrates the optimization and implementation techniques necessary for scaling the core-log derived (small scale) absolute permeability to the effective permeability data derived from pressure transient analysis (large scale). This unique approach was accomplished by first integrating reservoir conditioned core data with wireline logs for zonation of reservoirs into flow units. Core derived Flow Zone Indicator (FZI), which is a function of the reservoir quality index (RQI) and normalized porosity (PHIZ), was used as a predictor variable in modeling the selected wireline log responses using an adaptive neuro-fuzzy logic inference system (ANFIS). Predicted FZI and resultant core-log derived permeability were then calibrated using a water-oil relative permeability model derived from a suite of special cores from the same flow zones. Core-log derived permeability was then fine-tuned with the pressure transient analysis in the same reservoirs of interest. The results of this study have provided valuable answers to water injectivity predictions in the thick and thinly bedded sand/shale sequence of the Ventura Avenue Field. Water injection profiles in these reservoirs are now better understood and, consequently, the reservoirs are better characterized for waterflood recovery optimization. Copyright 2012, Society of Petroleum Engineers. Source


Alpert L.A.,University of Southern California | Alpert L.A.,Aera Energy LLC | Miller M.S.,University of Southern California | Becker T.W.,University of Southern California | Allam A.A.,University of Southern California
Journal of Geophysical Research: Solid Earth | Year: 2013

Upper mantle heterogeneity beneath the Alboran Sea (western Mediterranean) as inferred from seismology has been associated with a range of subduction and lithospheric delamination scenarios. However, better constraints on the deep dynamics of the region are needed to determine the cause and consequence of complex surface tectonics. Here, we use an improved set of shear wave splitting observations and a suite of mantle flow models to test a range of suggested structures. We find that the observed seismic anisotropy is best reproduced by mantle flow models that include a continuous, deeply extending slab beneath the Alboran which elongates along the Iberian margin from Granada to Gibraltar and curves southward toward the High Atlas. Other models with detached slabs, slabs with spatial gaps, or drip-like features produce results inconsistent with the splitting observations. SW-directed shear flow, when combined with sublithospheric deflection in response to a dense sinker, generates NNW-splitting orientations most similar to the patterns observed along Gibraltar. Slab viscosities of ∼250 times that of the upper mantle are preferred because they provide a balance between the poloidal flow induced by any sinker and toroidal flow induced by stiff slabs. The best match to anisotropy across the Atlas is a model with a stiff continental keel in northwestern Africa which deflects flow northward. Our results show that quantitative predictions of seismic anisotropy are useful in distinguishing the spatial and depth extent of regional density structures which may otherwise be ambiguous. © 2013. American Geophysical Union. All Rights Reserved. Source


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. Copyright © 2012 Society of Petroleum Engineers. Source


Ganev P.N.,University of Southern California | Ganev P.N.,Aera Energy LLC | Dolan J.F.,University of Southern California | Mcgill S.F.,California State University, San Bernardino | Frankel K.L.,Georgia Institute of Technology
Geophysical Journal International | Year: 2012

We present new slip rate estimates for the central Garlock fault. The incised edge of an alluvial fan deposit with a 10Be cosmogenic radionuclide age of 13.3 +5.9/-1.1 ka is offset 70 ± 7 m yielding a slip rate of 5.3 +1.0/-2.5 mm yr -1. A stream thalweg that is deeply incised into this surface is offset a lesser amount (58 ± 4 m) providing the lower bound for this rate. Climate considerations, however, suggest that the deep incision of this thalweg may have occurred at a younger date, specifically at the end of the Younger Dryas period at ∼11.5 ka or at the onset of a summer monsoon rainfall pattern at ∼8-10 ka. If the deep incision was related to one of these climate events, then the resulting slip rate would be 5.1 ± 0.3 and 6.6 ± 1.2 mm yr -1, respectively. All of the slip rates are consistent with previous geologic slip rates, most of which suggest a latest Pleistocene-Holocene slip rate of ∼5-7 mm yr -1. These geologic slip rates, however, contrast markedly with much slower (at most half as fast) short-term rates of elastic strain accumulation constrained by geodesy. The new slip rate thus adds to a growing body of evidence indicating that the Garlock fault is experiencing a period of transient lack of strain accumulation, in which the lower crust (and mantle?) beneath the fault is deforming at a rate that is much slower than its long-term average rate. These observations suggest that the Garlock fault experiences two modes of strain accumulation: the current 'slow' mode, in which strain accumulates very slowly along the fault, and 'fast' mode, during which the fault must store and release elastic strain energy at much faster rates than the long-term average to account for the relatively rapid geologic slip rates measured along the central part of the fault. © 2012 The Authors Geophysical Journal International © 2012 RAS. Source

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