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Acoustic velocity log numerical simulation and saturation estimation of gas hydrate reservoir in Shenhu area, South China Sea.

Xiao K, Zou C, Xiang B, Liu J - ScientificWorldJournal (2013)

Bottom Line: In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases.This rule is almost consistent with the previous research result.In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate.

View Article: PubMed Central - PubMed

Affiliation: School of Geophysics and Information Technology, China University of Geosciences, Beijing 10083, China.

ABSTRACT
Gas hydrate model and free gas model are established, and two-phase theory (TPT) for numerical simulation of elastic wave velocity is adopted to investigate the unconsolidated deep-water sedimentary strata in Shenhu area, South China Sea. The relationships between compression wave (P wave) velocity and gas hydrate saturation, free gas saturation, and sediment porosity at site SH2 are studied, respectively, and gas hydrate saturation of research area is estimated by gas hydrate model. In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases. This rule is almost consistent with the previous research result. In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate. The average value of gas hydrate saturation estimated from the TPT model is 23.2%, and the maximum saturation is 31.5%, which is basically in accordance with simplified three-phase equation (STPE), effective medium theory (EMT), resistivity log (Rt), and chloride anomaly method.

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The conventional logs in site SH2 [10]. (The area delineated by a pink line is the occurrence of gas hydrate reservoir, and the depth range is 195 to 220 mbsf.)
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fig2: The conventional logs in site SH2 [10]. (The area delineated by a pink line is the occurrence of gas hydrate reservoir, and the depth range is 195 to 220 mbsf.)

Mentions: During April–June 2007, eight sites were drilled in Shenhu area (see Figure 2), among which, sites of SH2, SH3, and SH7 in water depth of 1105 to 1423 m were determined to contain gas hydrate in recovered core samples. The thickness of gas hydrate stability zone was about 10 to 25 m [9, 49], and the sediment lithology in and above the zone was silt and silty clay respectively, according to the core data.


Acoustic velocity log numerical simulation and saturation estimation of gas hydrate reservoir in Shenhu area, South China Sea.

Xiao K, Zou C, Xiang B, Liu J - ScientificWorldJournal (2013)

The conventional logs in site SH2 [10]. (The area delineated by a pink line is the occurrence of gas hydrate reservoir, and the depth range is 195 to 220 mbsf.)
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3713345&req=5

fig2: The conventional logs in site SH2 [10]. (The area delineated by a pink line is the occurrence of gas hydrate reservoir, and the depth range is 195 to 220 mbsf.)
Mentions: During April–June 2007, eight sites were drilled in Shenhu area (see Figure 2), among which, sites of SH2, SH3, and SH7 in water depth of 1105 to 1423 m were determined to contain gas hydrate in recovered core samples. The thickness of gas hydrate stability zone was about 10 to 25 m [9, 49], and the sediment lithology in and above the zone was silt and silty clay respectively, according to the core data.

Bottom Line: In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases.This rule is almost consistent with the previous research result.In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate.

View Article: PubMed Central - PubMed

Affiliation: School of Geophysics and Information Technology, China University of Geosciences, Beijing 10083, China.

ABSTRACT
Gas hydrate model and free gas model are established, and two-phase theory (TPT) for numerical simulation of elastic wave velocity is adopted to investigate the unconsolidated deep-water sedimentary strata in Shenhu area, South China Sea. The relationships between compression wave (P wave) velocity and gas hydrate saturation, free gas saturation, and sediment porosity at site SH2 are studied, respectively, and gas hydrate saturation of research area is estimated by gas hydrate model. In depth of 50 to 245 m below seafloor (mbsf), as sediment porosity decreases, P wave velocity increases gradually; as gas hydrate saturation increases, P wave velocity increases gradually; as free gas saturation increases, P wave velocity decreases. This rule is almost consistent with the previous research result. In depth of 195 to 220 mbsf, the actual measurement of P wave velocity increases significantly relative to the P wave velocity of saturated water modeling, and this layer is determined to be rich in gas hydrate. The average value of gas hydrate saturation estimated from the TPT model is 23.2%, and the maximum saturation is 31.5%, which is basically in accordance with simplified three-phase equation (STPE), effective medium theory (EMT), resistivity log (Rt), and chloride anomaly method.

Show MeSH
Related in: MedlinePlus