{"id":1725,"date":"2021-07-30T23:21:51","date_gmt":"2021-07-30T23:21:51","guid":{"rendered":"https:\/\/ofgeomech.com\/ofg20\/?page_id=1725"},"modified":"2021-07-31T00:27:56","modified_gmt":"2021-07-31T00:27:56","slug":"reservoir-compaction-subsidence","status":"publish","type":"page","link":"https:\/\/ofgeomech.com\/ofg20\/reservoir-compaction-subsidence\/","title":{"rendered":"Reservoir Compaction & Subsidence"},"content":{"rendered":"\n
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Fundamentals<\/strong><\/h4>\n\n\n\n

Compaction<\/em><\/strong> occurs due to a pressure decline (often associated with fluid production), which causes the effective stresses to increase and a highly deformable rock to compact. Formation compaction<\/em><\/strong> occurs independent of the produced fluid type – whether hydrocarbons or water – and many of the most notable compaction events (Mexico City, US Gulf Coast, Venice) are driven by groundwater withdrawl. <\/p>\n\n\n\n

There are three primary contributors to significant compaction (i.e., inelastic compaction):<\/p>\n\n\n\n

  • \u2022 High formation compressibility<\/em><\/strong> (often reflected as high porosity);<\/li>
  • \u2022 Significant formation (compactable) thickness; and<\/li>
  • \u2022 Significant pressure decline (i.e., increase in normal effective stress).<\/li><\/ul>\n\n\n\n

    While compaction<\/em><\/strong> is the thinning of a depleted subsurface formation, compaction results in downward movement of the overlying formations. Depending upon the magnitude of vertical compaction and the aerial extent of the compacting region, the overlying formation movements may translate to a surface depression or surface subsidence<\/em><\/strong>.<\/p>\n\n\n\n

    The translation of reservoir compaction and overburden stress\/strain changes through to surface subsidence may reactivate overburden faults or create bedding slippage effects. In addition, surface subsidence<\/em><\/strong> can affect surface structures such as buildings, roadways, offshore platforms and pipelines.<\/p>\n\n\n\n

    Reservoir Compaction and Subsidence Modeling<\/strong><\/h4>\n\n\n\n

    While early compaction and subsidence evaluations were conducted with simple analytical models, proper reservoir compaction and subsidence evaluations require a full-field, 3D geomechanical mechanistic model<\/em><\/strong> in order to to evaluate:<\/p>\n\n\n\n