Geology and Geohistory Contribute to Flow Assurance

Yonebayashi, Hideharu; Tosic, Slavko; O'Brien, Dennis R.

doi:10.2118/154585-pa

Cited by 5 publications

(1 citation statement)

References 13 publications

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“…This work consistently requires some novel contrivance to understand the underlying mechanics of asphaltene behavior whereas apparent contradictions are often encountered. For example, the asphaltene onset pressure (AOP) is detectable at some locations but not others 14), 15) , and some asphaltene deposits observed in the field have not been detected from experimental predictions 13) . This article is therefore motivated by the need to summarize the practical lessons learned with regards to asphaltene issues in industry.…”

Section: Introductionmentioning

confidence: 99%

Asphaltene Flow Assurance Risks: How Are Pitfalls Brought into the Open?

Yonebayashi

2021

J. Jpn. Petrol. Inst.

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Section: Introductionmentioning

confidence: 99%

Asphaltene Flow Assurance Risks: How Are Pitfalls Brought into the Open?

Yonebayashi

2021

J. Jpn. Petrol. Inst.

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Contribution from Laboratory to Field: Case Studies of Asphaltene Precipitation Risk Evaluation

2016

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Three case studies pertaining to the precipitation risk of asphaltene, which comprise comprehensive evaluation from laboratory measurement to practical feedback into the field, are described. Two cases included aspects of gas injection, and the third corresponds to formation damage at a naturally depleted field. Asphaltene onset pressure (AOP) is a fundamental characteristic that represents in situ asphaltene behavior from a single-phase fluid sample; therefore, all evaluations were performed on the basis of laboratory-measured AOP data. The evaluations reported reveal how practical interpretation of laboratory-measured AOPs links appropriately to actual on-site phenomena. In the first two case studies, numerical asphaltene fluid models, calibrated using measured AOPs, were generated to evaluate asphaltene precipitation envelopes (APEs) by applying the cubic plus association equation of state. In the first case, a sensitivity analysis based on a numerical model of the original reservoir fluid was performed for several injection gases to investigate the impact of gas injection on APE behavior from the subsurface and surface points of view. In the second study, the variation of asphaltene deposits, actually observed at the gas injection pilot area, was explained by considering the vaporizing gas drive (VGD) process in terms of APE behavior. A sensitivity study was conducted to estimate how enriching the injection gas by this effect could expand the APE. An expanded APE could cause the variation of asphaltene deposits observed in the field: deposits were observed at certain times when enriched injection gas was accumulated but not when lean injection gas accumulated. Control of pressure depletion is considered an effective countermeasure to mitigate asphaltene precipitation in a naturally depleted field. For a field with a potential asphaltene deposition problem in the reservoir, it is recommended to maintain the reservoir pressure above the AOP. Such mitigation needs reliable AOP data. Once destabilized, solid particles of asphaltene grow continuously from the nanoscale (precipitation) to the microscale by aggregation. Our AOP measurements adopted the latest laboratory techniques. Three data sets were acquired using filtration, high-pressure microscopy analysis, and laser light scattering techniques. Despite using the same single-fluid sample, the AOP results were not identical because each measuring technique had different detection limits for the minimum asphaltene particle size. This paper demonstrates how we assessed the AOP data to determine the cause of asphaltene-induced formation damage by comparison to actual flowing bottomhole pressure behavior. This practical AOP measurement could suggest a more optimum pressure control target that would allow for maximum oil production while mitigating production potential loss as a result of shutdown for cleanup or removal jobs.

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Geology and Geohistory Contribute to Flow Assurance, Part II: Asphaltene Risk Evaluation Incorporating Geological Heterogeneity and Covering All Operating Temperature

Yonebayashi

Tosic

2013

EAGE Annual Conference &Amp; Exhibition Incorporating SPE Europec

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In the Kashagan field, a super giant offshore carbonate field, located in the North Caspian Sea, asphaltene risks have been continuously under evaluation. The previous work done by Yonebayashi et al. (2012) 1 included asphaltene risk evaluation incorporating geology and geohistory. Work showed good correlation between fluid sampling location and experimental asphaltene onset pressure (AOP) detection at reservoir temperature. However, a boundary condition of asphaltene precipitation/no-precipitation had some range of uncertainty. The previous work focused at the reservoir temperature condition only.This paper will present more detailed discussion of asphaltene risk by updating new AOP results, and it will capture range of temperature conditions (i.e. from reservoir temperature to surface operating temperature). For integrating these updates into the Risk-Matrix-Chart proposed in the previous work, geological heterogeneity of fluid sampling location will be taken into account. A study of numerical modeling, applying Redich-Kwong-Soave (RKS) cubic equation of state, treated the geological heterogeneity as variation of asphaltene content, and reproduced asphaltene precipitation envelopes (APE) which were well matched to overall trend of experimental AOP detection. To conclude, this work achieved to reduce uncertainty of asphaltene precipitation boundary at reservoir temperature, and showed a consistent shifting of asphaltene precipitation boundary by temperature range. AuthorsHideharu Yonebayashi is currently working as a secondee for ExxonMobil Development Co. He has 19 years experience in the oil industry and his expertise includes microbial enhanced oil recovery, gas injection, SAGD, flow assurance evaluation and supervising of field operations (acidizing, asphaltene removal, well test, PLT, etc.). His main interests are EOR and related technologies. He holds BS, MS and PhD degrees from the Tohoku University, Japan, all in petroleum engineering. Slavko Tosic is working for ExxonMobil and is currently seconded to NCOC. His work experience and research areas include reservoir simulation, well testing, multiphase metering, advance production and reservoir analysis, fluid behavior, and field development. He holds a BS and MS degrees in petroleum engineering from University of Belgrade and Texas A&M University, respectively.

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Geology and Geohistory Contribute to Flow Assurance

Cited by 5 publications

References 13 publications

Asphaltene Flow Assurance Risks: How Are Pitfalls Brought into the Open?

Asphaltene Flow Assurance Risks: How Are Pitfalls Brought into the Open?

Contribution from Laboratory to Field: Case Studies of Asphaltene Precipitation Risk Evaluation

Geology and Geohistory Contribute to Flow Assurance, Part II: Asphaltene Risk Evaluation Incorporating Geological Heterogeneity and Covering All Operating Temperature

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