太平洋炭鉱における切羽出水に関する研究 (第3報)

含水層と含水層中の貯留ガスについて

抄録

As we previously stated in the 1st report (1957) and the 2nd report (1959), thewriters carried out a research on the water reservoir of the cretaceous formationunderlying the Harutori coal bearing formation.
With newly obtained data for 20 years, it is our intention to describe herewith conditions of the water reservoir and filling lnflammblae gas, which can be summarised as follows:
1. The distribution of the chlorine content in the water reservoir has the same pattern with the general trend of the geological structure, the content increasing as the reservoir becomes deeper: contour intervals of the Cl content correlate with the depth of the reservoir, fine nearer the surface and coarse at deeper levels, and fixed at about13, 000mg/L. The area of Minami-Masuura, however, has peculiar features.
2. The thickness of the water reservoir is 40m-50m, the voids ratio at the Harutori area is about 6%, and the fissures of the reservoir are almost horizontal and cross with angles of 70°-80°.
3. By boring and drainage wells, each water level of the reservoir has been proved different by one block of geological structure as shown in Fig. 1.
4. The cavity occurred due to lowering of the water level of the reservoir is filled with inflammable gas separated from the connate water.
5. The initial pressure of the gas filling in the cavity is 0.5kg/cm², and the gas water ratio of the connate water is calculated pretty higher than the theoretical value.
6. The Fig. 4 shows the gas productivity index of the reservoir as a regional feature indicating quantity of the waterspout and the production rate of the gas.
7. The Table 5 indicates free gas resources of the water reservoir by one block of the geological structure. We estimated the annual production with the present reserve as 5, 000, 000 cm³, and taking account of the increase by pondering connate water, the possibility can be higher.