Zeolitic alteration of vitric tuffs from the Neogene oil-bearing deposits of the Noshiro basin (Fig. 1) in the Akita oil field shows regular zonal arrangements, in descending order as (Fig. 2), fresh glass zone-clinoptilolite zone-analcime zone-authigenic albite zone. Each zeolite zone considerably varies with the localities (Figs. 3 and 4) in both stratigraphic horizons and thickness. The natural densities of the mudstone at the top of the clinoptilolite zone is measured to be 1.87± and that of the analcime zone 2.15± (Fig. 5). From the thickness of the strata (Fig. 6) above the mudstone, the initial thickness before burial is calculated to be 830m+ above the clinoptilolite zone and 1500m+ above the analcime zone. The zeolitic alterations of the vitritic tuffs in the Noshiro basin are interrelated to their overburden thickness (Figs. 7-11). Such differences of sedimentation are inferred to be due to the differential movements of the sedimentary basin caused by the Dewa Disturbance during the later Funakawan and the early Tentokujian stages.
Many faults were encountered in the Hout Field wells which are located in the Arabian Oil Company's concession area in the Arabian Gulf (Persian Gulf). These faults were analyzed mainly on the basis of Schlumberger's Continuous Dipmeter results and other well data, and interpreted to be the radiated rupture-fults which occurred on the surface formations with small wedge-shaped blocks slipped down into the rupture bottom at the time of upheaval movement which formed the Hout anticlinal structure at the end of Middle Cretaceous. The horizontal distribution manner of faults is a radial form with a center on the crest of the structure. The bottom of each couple of ruptures, that is, each wedge-shaped block, seems not to reach the Ratawi Horizon. So, the rupture faults are limited to the Middle Cretaceous forma tions. Then, these faults never give any affect to the Ratawi reservoir continuity and oil accumulation but give some affects to the Middle Cretaceous reservoirs.