This is the last part of our paper, the "Part 1" and "Part 2" of which appeared in the Journal of the Japanese Association of Petroleum Technologists, Vol.35 No.4 and No.7 respectively.
Firstly abundance ratio of benzen/n-heptane and sulfur content of the Minami-Age crude are discussed. In general these parameters are thought to decrease concurrently with the secondary migration and accumulation of oil. In the A and C blocks the abundance ratio decreases with the decrease in the depth of reservoir. But in the B block such a trend is not recognized (Fig. 23). This is probably due to the higher solubility of benzen in water rather abnormal reservoir conditions of the B block including water saturation, reservoir thickness, dip, etc. In Figure 24 the abundance ratios are plotted in the order along the dashed line shown in Figure 25. Generally, the B block crude has smaller values of the abundance ratio and there is a tendency that the oils from the portions of highest water saturation have the smallest values of the ratio. As for the sulfur content, it has clear correlations with the specific gravity of oil and the depth of the reservoir (Fig. 26). There is no correlation between sulfur content and the situation of the wells (Fig. 27). From these facts it is considered that the oil did not migrate in a single particular direction.
Next, we discuss the results of liquid-chromatographic analysis of the crude. With regard to the 275-300°C cut, the amount of aromatics of the A block crude is larger than that of the B and C block crudes (Fig. 28.), which resembles more or less benzene/n-heptane ratio (Fig. 24).
Reverting to the descriptions and discussions in the "Part 1", "Part 2" and "Part 3", we have reached some conclusions. Among these, some of the significant ones are given as follows:
(1) The crude oil from the Minami-Age field is more evolved than that from the Kubiki field. This may result mostly from the higher temperature of the reservoir. And, a clear distinction can be drawn between these two crudes.
(2) The oils from 24 producing wells in the Minami-Aga field have probably been derived from a single origin.
(3) From many reservoir data and the measurement of the specific gravity of oil the field can be deviled into 3 blocks. i. e. the A, B and C. The reservoir conditions of the B block are more or less different from those of the A and C blocks. But even the reservoir conditions of the B block are less complicated than those of the Kubiki (Katamachi) Ie reservoir.
(4) The abundance ratios of hydrocarbon isomers that would characterize the Minami-Aga crude to some extent and may have been kept more or less constant during the time of secondary migration and accumulation of oil are those shown in Figures 12, 16 and 18.
(5) Some of the abundance ratios of hydrocarbon isomers seem to have correlations with the specific gravity of oil and various reservoir parameters. In such cases the B block crude often shows somewhat different trends from the crudes from the A and C blocks, probably reflecting the anomalous reservoir conditions of the B block.
(6) The oil may have migrated from the suburbs of an anticline; on a plane figure the direction of lateral migration would not he limited to a particular azimuth.
(7) After the accumulation of oil the f-f' faulting took place, thereby forming two plunging anticlines. Secondary alteration of the B block crude is thought to have occurred after the faulting.

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The writer presents here the result of his geometrical structural analysis of Cretaceous System which crops out in south central part of Hokkaido. Cretaceous geology is megascopically compiled on the basis of photo-geologic interpretation (Fig. 1).
Of two commonly used stereographic methods (Wulff's net, lower hemisphere projection), π-diagram (S-pole diagram) is adopted for finding the direction of fold axis. Measurements of 1598 bedding planes observed in the surveys conducted by his many colleagues before 1961, have been used as data for construction. Some typical projections are figured as several kinds of stereogram (Fig. 2).
Structural homogeneity decided from regular orientation (acute distribution of S-poles on great circle on the net) of π-diagram, isdiscernible in the intrasub-area. Orientation of axial surfaces and fold axes are shown (Fig. 3 and 4), from which fold forms are inferred. Taking into consideration the subareal S-poles counting densities (Fig. 5), structurally homogeneous domains have been studid (Fig. 6).

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During the past 20 years members of the petroleum industry have proposad more than fifteen new or novel recovery methods for increasing the ultimate oil or gas recovery. This paper is a general review of these new methods. A simple description of the new and improved recovery processes and their range of application is presented. The methods discussed include wet combustion, forward combustion, reverse combustion and combustion with fuel injection. The miscible process of high pressure gas, enriched gas and LPG slugs, are covered. Use of micellar solutions, alcohol and foam flooding is covered. The application of atomic bombs for well completions is discussed.

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