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The AAPG/Datapages Combined Publications Database

Houston Geological Society Bulletin

Abstract


Houston Geological Society Bulletin, Volume 34, No. 1, September 1991. Pages 13-13.

Abstract: Petrophysical Properties of Seals

By

Robert M. Sneider

Seals are defined as generally ductile rocks with a very high capillary entry pressure which can dam up hydrocarbons. Petrophysical and petrographic studies of conventional and sidewall cores from known Previous HitsealNext Hit-reservoir couplets of hydrocarbon-producing reservoirs provide a basis to quantify the capacity of a rock to trap a hydrocarbon column. The most important property of a Previous HitsealNext Hit is its pore size distribution as measured in thin section, scanning electron microscope and very high pressure (up to 50,000 psi) air-mercury capillary pressure curves determined across bedding surfaces in vertical plugs.

Previous HitSealNext Hit quality or capacity is determined by pore-size distribution and interconnection, and Previous HitductilityNext Hit. Using the density difference of normal saline water and 35° API gravity oil as a standard, an arbitrary scale of Previous HitsealNext Hit types is defined:

Previous HitSEALNext Hit TYPES
35° API Oil Column Held

 

  METERS   FEET
TYPE A

>300

 

>1000

TYPE B >150                  <300   >500                          <1000
TYPE C >30                    <150   >100                            <500
TYPE D >15                      <30   >50                              <100
TYPE E

<15

 

<50

TYPE F WASTE ZONE ROCKS

Comparators of known Previous HitsealNext Hit types composed of samples of the rock type, SEM photographs and capillary pressure curve are used to estimate Previous HitsealNext Hit type under a binocular microscope at 50X magnification. A catalogue of petrophysical properties and photomicrographs allows one to make reliable estimates of Previous HitsealTop capacity of unknown samples in cores and cuttings with a binocular microscope.

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