Errors Associated with Waterflood Monitoring Using the Hall Plot for Stacked Reservoirs in the Absence of Profile Surveys

Qi, Qianru; Pepin, Sophie; AlJazzaf, Abdula; Ershaghi, Iraj

doi:10.2118/185694-ms

Cited by 3 publications

(1 citation statement)

References 5 publications

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“…In previous studies, Hall's method was applied for evaluating the performance of water flooding [6][7][8][9][10][11], water flooding in multilayer reservoirs [12][13][14], immiscible gas flooding [15], steam flooding [16][17], polymer flooding, [18], and water flooding in geothermal reservoir [19].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Performance of Injection Wells in EX Structure

Antariksa¹,

Irawan

Ratnaningsih

et al. 2022

Journal of Earth Energy Science, Engineering, and Technology

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One of the efforts that can be done to evaluate the performance of water injection in a field is by monitoring the injector wells. Observations can be made by looking at the flow rate and injection pressure at each injector well. The response given by each injection well will be able to represent the injection performance on a field scale. The EX structure is a structure that has been produced for more than 40 years. In addition, water injection has also been applied for approximately 16 years. There are four injection wells operating in this EX structure with an average injection flow rate of 3000-8000 bwipd per well. Evaluation of injection well performance is carried out by conducting a Hall Plot on each injection well from the start of the injection process to the last data obtained. Based on the evaluation results, it was found that there was plugging in the EA-IIS and EJ-IVS injection wells. Stimulation activity is needed in both wells to restore the well injection capability. Meanwhile, for the EA-IS and EB-IIL injection wells, there are no significant problems in those wells so they can still function properly as injection wells.

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Section: Introductionmentioning

confidence: 99%

Evaluation of the Performance of Injection Wells in EX Structure

Antariksa¹,

Irawan

Ratnaningsih

et al. 2022

Journal of Earth Energy Science, Engineering, and Technology

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Predicting and Applying Wellhead Temperatures for Steamflood-Field Operation and Production-Performance Monitoring

Yang¹

2020

SPE Reservoir Evaluation &Amp; Engineering

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Summary Producer-flowline temperatures (FLTs) can be measured automatically with a thermistor on an emergency-shutdown system (ESD), or manually on a specified spot on flowline with a handheld unit. Measured FLTs can usually be mapped to represent the formation-temperature distribution for steamflood reservoir management purposes (Hong 1994; Nath et al. 2007). In addition to FLT, wellhead temperature (WHT) is another surface temperature. Predicting the long-term WHT trend in steamflood operation is necessary for designing surface facilities for both oil dehydration/separation and produced-water recycling. This predicted temperature will also be applicable for production-performance monitoring. To predict the wellhead temperature, Hasan et al. (2009) derived a steady-state analytical solution for calculating WHT from bottomhole temperature (BHT) under flowing conditions of a multisection slant wellbore for the isothermal primary-depletion process, with both WHT and BHT being time independent for a given gross rate (Igec et al. 2010). This steady-state analytical solution has been extended to calculate steamflood producer WHT from BHT (both are time dependent) by consecutively approximating the WHT and monthly average of FLT measurements to a steady-state solution. The monthly averaged FLTs are seasonally variable and higher in the summer months of July through September and lower in the winter months of December through February. Monthly averaged FLT measurements depend on an annual ambient-temperature cycle within the depth needed for reaching an undisturbed ground temperature (typically 30 to 50 ft) (Gwadera et al. 2017). WHT, if measured, should be comparable with FLT for their close typical distance of 5 to 10 ft. WHT prediction, however, is only process dependent and not seasonally variable because of the inability to describe seasonally undisturbed depth in the geothermal gradient. Therefore, WHT prediction can be validated with average summer-month FLT measurements when heat loss becomes minimal. BHTs in this analytical approach are predicted by the Lauwerier (1955) analytical model and improved by calibration with the available reservoir-simulation model or several years of FLT measurements for steamflood response time. The objective of this study is to develop an integrated production-monitoring approach using only the surface information, including WHT and FLT, oil/water-production rate, and injection-pressure/rate data, which can be applied to diagnose and optimize steamflood production performance. A field case study for the South Belridge Diatomite steamflood was investigated. WHT prediction is compared with FLT measurement for diagnosing and understanding the production performances, such as premature water or steam breakthrough, interference by the waterflood on the steamflood boundary producers, as well as the FLT variation related to the target rates for steam injection. This diagnostic analysis approach combined with the Buckley-Leverett theory-based displacement-efficiency analysis, and injection pressure and rate signal, will help to develop an improved understanding of the displacement detail and form a decision base to optimize the production performance.

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Saturation Dependent Errors in Interpreting Waterflood Diagnostic Plots

Ershaghi

2019

SPE Western Regional Meeting

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Various diagnostics plots related to examining injection pressure gradient requirements for maintaining injectivity have been used in waterflood management. Among these plots, Hall plots and the derivative of Hall plots are the most common approaches used in the industry. This paper includes an analysis of some errors associated with interpreting Hall plots and the derivative of Hall plots in monitoring waterfloods. Based on observations from several waterfloods in California, in this paper we demonstrate by numerical modeling, that the cause of slope flattening can also be dependent on the state of saturation history around injection wells. We also show that the flattening can be compensated by skin build up resulting in misleading trends. We conducted a series of numerical modeling work to examine these issues. From such modeling experiments, we considered cases of injection well behavior in virgin reservoirs as well as in mature waterfloods. We show that when new injectors are drilled, water saturation buildup tends to flatten the slope observed on the Hall Plot or the derivative of Hall plot. For new floods, drops in the slope observed can be associated with water saturation buildup caused by limited flooding history. When injection wells are drilled in flooded segments of a field, such saturation dependent flattening may not be observed. This is a significant issue as it affects decisions related to restriction limits on injection gradient as well as unnecessary stimulation work. In summary, we conclude that interpretation of Hall plots without consideration of water saturation history can be misleading.

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Errors Associated with Waterflood Monitoring Using the Hall Plot for Stacked Reservoirs in the Absence of Profile Surveys

Cited by 3 publications

References 5 publications

Evaluation of the Performance of Injection Wells in EX Structure

Evaluation of the Performance of Injection Wells in EX Structure

Predicting and Applying Wellhead Temperatures for Steamflood-Field Operation and Production-Performance Monitoring

Saturation Dependent Errors in Interpreting Waterflood Diagnostic Plots

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