Visual analysis on the effects of fracture-surface characteristics and rock type on proppant transport in vertical fractures

Hai Huang, Tayfun Babadagli, Huazhou Andy Li, Kayhan Develi

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

22 Citations (Scopus)

Abstract

The fracture-surface characteristics (such as roughness and fractal dimensions) may greatly affect the proppant transport during hydraulic fracturing operation. Few researches have focused on investigating the proppant transport in vertical fracture with actual surface characteristics. As a continuation of our previous study (Huang et al. 2017), we qualitatively investigatethe migration of proppants in rough and vertical fractures by considering the effects of surface characteristics and rock type on the instantaneous transport and areal spreading of proppant in the fractures. We fractured different types of tight rocks (including limestone, marble, tight sandstone, and granite) with Brazilian test and molded them to manufacture 20×20cm transparent replicas with an aperture of 1 mm. We characterized the surface characteristics of these rock samples with different fractal dimensions. Subsequently, dyed fracturing fluid with or without proppant loading was injected into the rough vertical fracture. In each test, we monitored the inlet pressure continuously while the proppants were being transported in the fracture. The process was videotaped to monitor the proppant distribution in the rough fracture. Different from our previous study (Huang et al. 2017), a higher injection rate is used in this present study. The experimental results obtained in this study further consolidate the many findings reported in our recent study (Huang et al. 2017): in rough and narrow fracture, the surface roughness plays a pivotal role in affecting how proppants settle in the fracture as well as where the proppants settle in the fracture. Roughness of the vertical fractures tends to significantly enhance the vertical placement of proppants in the fracture, leading to a much higher proppant-filling ratio in a rough fracture than in a smooth fracture. Interestingly, in addition to the bridging effect observed in Huang et al. (2017), a previously formed proppants cluster can be broken up under a higher-rate slurry flow. The bridging of proppants and its subsequent breaking up can recursively occur during the high-rate slurry flow, resulting in fluctuations in the proppant filling ratios as well as fluctuations in the pressure profiles recorded in the inlet of the fracture model. The roughness of fracture models not only affects how much area of the fracture is being occupied by the proppants in the fracture, but also affects how tightly the proppants are filling up the fracture. Different types of rock have different surface characteristics, leading to the observed differences with regard to how the proppants migrate, settle down and fill up the fractures. No definite correlation could be established between any of the fractal numbers and the relative coverage of proppants in the fracture. More experiments, however, need to be conducted to reach more concrete conclusions in this regard.

Original languageEnglish
Title of host publicationSociety of Petroleum Engineers - SPE Hydraulic Fracturing Technology Conference and Exhibition 2018, HFTC 2018
PublisherSociety of Petroleum Engineers
ISBN (Print)9781510858244
DOIs
Publication statusPublished - 2018
EventSPE Hydraulic Fracturing Technology Conference and Exhibition 2018, HFTC 2018 - The Woodlands, United States
Duration: 23 Jan 201825 Jan 2018

Publication series

NameSociety of Petroleum Engineers - SPE Hydraulic Fracturing Technology Conference and Exhibition 2018, HFTC 2018

Conference

ConferenceSPE Hydraulic Fracturing Technology Conference and Exhibition 2018, HFTC 2018
Country/TerritoryUnited States
CityThe Woodlands
Period23/01/1825/01/18

Bibliographical note

Publisher Copyright:
© 2018, Society of Petroleum Engineers

Funding

This research was conducted under T. Babadagli's NSERC Industrial Research Chair in Unconventional Oil Recovery (industrial partners are APEX Eng., Devon, Husky Energy, Petroleum Development Oman, Saudi Aramco, SIGNa Oilfield Canada, Total E&P Recherché Développement) and NSERC Discovery Grants No: RES0011227 (T. Babadagli) and RGPIN 05394 (H. Li), respectively. H. Huang is also grateful for the financial supports provided by National Science and Technology Major Project (No. 2016ZX05047003-004) the Shaanxi Industrial Science and Technology Research Project (No.2015GY109), the Key Laboratory Fund of Education Department of Shaanxi Province (No.15JS086) as well as the Xi'an Shiyou University for supporting his stay at the University of Alberta. We gratefully acknowledge these supports.

FundersFunder number
Husky Energy, Petroleum Development Oman
Key Laboratory Fund of Education Department of Shaanxi Province15JS086
Shaanxi Industrial Science and Technology Research Project2015GY109
Natural Sciences and Engineering Research Council of Canada
University of Alberta
Saudi AramcoRES0011227, RGPIN 05394
Xi'an Shiyou University
Science and Technology Major Project of Guangxi2016ZX05047003-004

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