By E Kofi Sakyiamah | #Well_Logging_Formation_Resistivity...
Formation Resistivity are sub T is important because it is inversely related to water saturation for example, in the uninvaded zone all other things remaining equal as the electrical resistivity of the formation decreases, the water saturation increases. Consequently, from changes in resistivity measurements we can determine changes in water saturation and therefore changes in hydrocarbon saturation.
In electrical logging, several factors control the measured electrical response. They are water saturation, salinity, porosity, and poor interconnections. Sometimes referred to as tortuosity. The first two of these factors are fluid dependent while the third is rock dependent.
Before looking at electrical logging techniques, let's examine how these factors influence our measurements. Starting of, our simple experiment with a sample of distilled water, we pass a constant electrical current from here to here and measure the voltage difference caused by the current flow between here and here.
As the salinity of the sample is changed, you can observe a change in the voltage reading and as we remove some of the water that is change the water saturation of our sample and replace it by another substance let's say oil, the voltage changes again.
Next, if we soak a sponge in our original distilled water sample to simulate a porous formation and again pass an electrical current through the electrodes, we obtain a different voltage reading as compared to the ideal high porosity case. That is, no formation and only fluid. The summation of our results reveals that as salinity increases, current flows between the current electrodes and there is a potential or voltage drop measured.
In logging terms, the conductivity of the sample formation increases which is the same as a decrease in resistivity. Next, as saturation decreases, the voltage measured increases and uniquely in resistivity terms now so does the resistivity and finally as porosity decreases, the voltage increases and so does the resistivity.
It is important to remember that resistivity is measured in all meters squared per meter and arises from its definition as the specific resistance through a sample of a certain length and cross-section. The poster, Emmanuel Kofi Sakyiamah, is an 8+ years experienced Petroleum Industry (Oil & Gas Crane Lifter/Rigger, HSSEQ, Materials Coordinator Professional, etc ) who has worked on several exploration and production projects in Africa with GNPC, LUKOIL, NARANS ENERGY, ENI, SPRINGFIELD E&P, etc. You can reach E. Kofi Sakyiamah on +233 245 170 917 or +233 050 200 80 89 to engage him for his professional services with integrity.
Reference(s) and Credit(s):
Harvest Chemical
Formation Resistivity are sub T is important because it is inversely related to water saturation for example, in the uninvaded zone all other things remaining equal as the electrical resistivity of the formation decreases, the water saturation increases. Consequently, from changes in resistivity measurements we can determine changes in water saturation and therefore changes in hydrocarbon saturation.
In electrical logging, several factors control the measured electrical response. They are water saturation, salinity, porosity, and poor interconnections. Sometimes referred to as tortuosity. The first two of these factors are fluid dependent while the third is rock dependent.
Before looking at electrical logging techniques, let's examine how these factors influence our measurements. Starting of, our simple experiment with a sample of distilled water, we pass a constant electrical current from here to here and measure the voltage difference caused by the current flow between here and here.
As the salinity of the sample is changed, you can observe a change in the voltage reading and as we remove some of the water that is change the water saturation of our sample and replace it by another substance let's say oil, the voltage changes again.
Next, if we soak a sponge in our original distilled water sample to simulate a porous formation and again pass an electrical current through the electrodes, we obtain a different voltage reading as compared to the ideal high porosity case. That is, no formation and only fluid. The summation of our results reveals that as salinity increases, current flows between the current electrodes and there is a potential or voltage drop measured.
In logging terms, the conductivity of the sample formation increases which is the same as a decrease in resistivity. Next, as saturation decreases, the voltage measured increases and uniquely in resistivity terms now so does the resistivity and finally as porosity decreases, the voltage increases and so does the resistivity.
It is important to remember that resistivity is measured in all meters squared per meter and arises from its definition as the specific resistance through a sample of a certain length and cross-section. The poster, Emmanuel Kofi Sakyiamah, is an 8+ years experienced Petroleum Industry (Oil & Gas Crane Lifter/Rigger, HSSEQ, Materials Coordinator Professional, etc ) who has worked on several exploration and production projects in Africa with GNPC, LUKOIL, NARANS ENERGY, ENI, SPRINGFIELD E&P, etc. You can reach E. Kofi Sakyiamah on +233 245 170 917 or +233 050 200 80 89 to engage him for his professional services with integrity.
Reference(s) and Credit(s):
Harvest Chemical
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