砂岩侵入体及其油气地质意义

Translated title of the contribution: Sand injectites and its petroleum geological significances

Zhufu Shao*, Wenxin Zhang, Cui Mao, Xiwu Luan, Jianhua Zhong, John Howell, Zexuan Liu, Bing Zhao, Weimin Ran, Jingjing Liu

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

Abstract

The good outcrops exposed along the California orogenic belt as well as successful exploration & development provide examples for the study of sandstone injections (injectites). Sandstone injections are widely developed in a variety of sedimentary systems from the Late Proterozoic to the Holocene of which deep-water systems are the most common ones. The lithology of injection is more frequently fine to medium-grained sandstone in turbidite fans, and the host layers are mainly mudstone and shale. Sand injections are comprised of 4 components including parent units, host strata, sand intrusion/extrusion, and the fracture systems and 5 types of sand dikes, sand sills, and columns/sand pillars, sand volcanos and injection complexes. The geometries of sand injection mainly consist of 3 types like saucer-wing shaped, conical shaped and crestal complex, and the top of the intrusion often develops mound shape. The interior part of sand injection is often structureless or laminated, with erosion boundaries and mass mud clasts, like a jigsaw. The formation conditions of intrusion include unconsolidated sand body, low-permeable overlain layers, pore fluid overpressure and dominant channel of the sand body. Seismic liquefaction, disequilibrium compaction, overburden, regional tectonic stress, and fluid flow are the most common triggering mechanisms. The formation process of intrusive body includes 5 processes:pore fluid overpressure, sand liquefaction, hydraulic fracturing and fluidization, sand injection and redeposition. Sand injections increase reservoir volume, link sand bodies together like conduits, and form injection traps. Sand injections can also be used to predict regional stress fields, but may also lead to failure of seals and water channeling. The determination of injecting time, geological process after injection and the deterministic study of triggering mechanisms are facing challenges. Interdisciplinarity, virtual outcrop, simulation experiments, and numerical simulation technology will be the future development direction.

Translated title of the contributionSand injectites and its petroleum geological significances
Original languageChinese (Traditional)
Pages (from-to)378-398
Number of pages21
JournalShiyou Xuebao/Acta Petrolei Sinica
Volume42
Issue number3
DOIs
Publication statusPublished - 1 Mar 2021

Keywords

  • Deep-water deposition
  • Hydrocarbon exploration
  • Injection reservoirs
  • North Sea field
  • Sand injection
  • Seismic liquefaction
  • Trigger mechanisms

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