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Core alteration and preservation (view source)
Revision as of 15:55, 7 January 2014
, 15:55, 7 January 2014→Wet core preservation methods
===Wet core preservation methods===
===Wet core preservation methods===
Cores can be preserved by submerging them in jars of deoxygenated formation brine or diesel. A bactericide, generally formaldehyde, is added to prevent bacterial growth during storage. The jars are closed and the system purged with nitrogen. This system inhibits most oxidation (Basan et al, 1988)<ref name=Basan_etal_1988 />.
Cores can be preserved by submerging them in jars of deoxygenated formation brine or diesel. A bactericide, generally formaldehyde, is added to prevent bacterial growth during storage. The jars are closed and the system purged with nitrogen. This system inhibits most oxidation.<ref name=Basan_etal_1988 />
Polycarbonate or anaerobic jars are the most commonly used containers. Other containers that can be used are made of steel, PVC, or glass. Caution must be exercised when using steel because it can rust in the presence of water. PVC containers are not optimal because they permit diffusion of water and oxygen (Basan et al., 1988)<ref name=Basan_etal_1988 />. Glass containers are excellent preservation containers, but they are difficult to use in the field without breaking.
Polycarbonate or anaerobic jars are the most commonly used containers. Other containers that can be used are made of steel, PVC, or glass. Caution must be exercised when using steel because it can rust in the presence of water. PVC containers are not optimal because they permit diffusion of water and oxygen.<ref name=Basan_etal_1988 /> Glass containers are excellent preservation containers, but they are difficult to use in the field without breaking.
The wet method of core storage is often used when the core analysis program requires maintaining wettability. There still some debate about which fluid should be used in the containers. Wet preservation cannot be used when cores are cut to evaluate interstitial water, to measure fluid levels, or to interpret gas, oil, or water production. This is because exposure of the core to a fluid results in imbibition of that fluid and alteration of saturations.
The wet method of core storage is often used when the core analysis program requires maintaining wettability. There still some debate about which fluid should be used in the containers. Wet preservation cannot be used when cores are cut to evaluate interstitial water, to measure fluid levels, or to interpret gas, oil, or water production. This is because exposure of the core to a fluid results in imbibition of that fluid and alteration of saturations.
Preserving and storing core with a wet system has a high cost and requires regular maintenance. Each jar must be purged with nitrogen every two weeks.
Preserving and storing core with a wet system has a high cost and requires regular maintenance. Each jar must be purged with nitrogen every two weeks.
==References==
==References==