Thermal maturation history of sedimentary rocks in the Niigata basin was estimated from the temperature history of sedimentary rocks which was determined from a paleotemperature and burial history of sediments, using Lopatin's method. Age of each formation and restored depth at each stage which was constructed after correcting an effect of compaction of sediments, provided a burial history of sediments. A paleotemperatute in the Niigata basin has been discussed in the part one of this paper. Time-temperature indices (TTI) were assessed from the temperature histories of sedimentary rocks on about one hundred wells. A following empirical equation was provided by plottings vitrinite refiectances (R0%) vs. TTI. log R0=0.07575 log TTI-0.2515 Estimated oil and gas generation areas at each stages from the Nanatani stage (15. M.Y.B.P.) to present were determined based on the results of the calculated maturation history. The distribution of oil and gas fields is in accord with estimated present oil and gas generation areas. Timings of migration to several oil and gas fields in the Niigata basin are interpreted based on the history of maturation and tectonic movement. The results are following. 1) Main hydrocarbon migration occured during and after the Nishiyama stage (0.-4.3M.Y.B.P.). 2) Main hydrocarbon migration to oil fields occured at the oil generation stage (0.5%_??_R0〈0.7%) of organic maturation levels. 3) Main hydrocarbon migration to gas fields occured at the gas generation stage (R0_??_0.7%) of organic maturation levels.
For safe and effective deepwater operations, one of the most important studies is to know the behavior of the riser pipe in maintaining the flexible joint angle and riser stress within operating limits which will be affected and varied by the environmental forces. This paper is aimed to establish the analytical methods and operating procedures for riser and mooring systems in deepwater operation in consideration of such significant factor. The analytical methods for riser and mooring systems in this study are determined by purposefully arranged equations currently common for computer aided analysis. In this part 1 of the study, theoretical discussions have been mainly described and verified by comparison with presently available published papers as the results of the engineering companies analysis which have been carried out for Japanese Government Stratigraphical Drilling Projects.
For safe and effective deepwater operations, one of the most important studies is to know the behavior of the riser pipe in maintaining the flexible joint angle and riser stress within operating limits which will be affected and varied by the environmental forces. This paper is aimed to establish the analytical methods and operating procedures for riser and mooring systems in deepwater operations in consideration of such significant factor. The part 1 of this study discussed about analytical methods and verifications. This paper as part 2 will discuss about the applications to the actual drilling projects to varify whether the operating procedures and recommendations hypothetically designated is considered to meet the requirements of keeping the drilling vessels practically operational and safe. The recommendations derived from this study have been applied to Japanese Government Stratigraphical Drilling Projects and are proved as satisfactory.