To examine on accuracy for data in natural gases and cuttings ones, some problems on sampling vessels, preservation period of small amounts of gases for stable isotope mass spectrometry and carbon dioxide preparation were discussed. As sampling containers, Tedlar bags, Teflon, polyethylene and glass were used. As the results, components in standard methane (δ13C: -65.4‰), changed to -58.2‰ in Tedlar bags, to -62.4‰ in Teflon, to -63.7‰ in polyethylene vessels, while not in glass vessels after one month. When production gas is used as a sample, the change of components showed same tendency as above. Residual gases in carbon dioxide preparation stage, especially from preceding concentrated gases, affected much on successive determinations. In 13C stable isotope ratio mass spectrometry, attentions should be on sampling vessels and on excluding residual gases in carbon dioxide preparation stage. Glass bottles are the most favourable for sampling and preservation of gases for the analysis.
To know about characteristics of crude oils with mass spectrometer, the carbon isotopic ratios measurements of 86 samples of crude oil from foreign and domestic fields were carried out. A quartz tube was used as a combustion vessel and vanadium pentoxide as an oxidation agent. A mixture of crude oil and vanadium pentoxide placed in the quartz tube was vacuumed and then sealed. This was heated for 2 hours at 900°C in electric furnace. Produced carbon dioxide was introduced to mass spectrometer to determine isotopic ratio. Foreign oil samples showed -27.7--22.0‰, as δ13C values. Results of domestic crude oils showed -24.0--24.1‰ in Hokkaidou, -24.5--21.9‰ in Akita, -23.7--21.7‰ in Yamagata, and -24.8--21.3‰ in Niigata, as δ13C values, which agreed well with the results of the Tertiary period oil in North America.
A new continuous technique has been developed for the rapid measurement of the effective thermal conductivity of cuttings-water mixture beds at simulated in situ geothermal conditions to estimate the effective thermal conductivity of rocks in situ by using the cuttings. The technique is based on a modified transient hot wire method to measure the thermal conductivity of poor conductors. Two kind of pure-fused-quartz-grains and water mixture beds were used as test samples. Mean diameters of the grains were 0.51mm for larger ones and 0.34mm for smaller ones. Measurements were made at a heating rate of 20°C/h from room temperature to about 110°C and at natural cooling conditions from the maximum heated temperature to the room temperature at their saturation pressures to verify accuracy of this technique. At the natural cooling conditions good results were obtained for the mixture beds. Thermal conductivity of the fused quartz grains estimated from the Kunii's formular and the effective thermal conductivity of the two samples which was obtained by the measurement agreed with literature data within the sum of experimental and estimating errors ±15.0%. The grain size effect for the grain's conductivity was negligible.