The southern Kanto gas-producing region is one of the most representative iodine-producing regions in Japan. It is originated in the younger marine sediments in the lower geothermal heat flow region (Fig. 1). The points on the Br--I- diagram representing Br- and I- contents (mg/l) calculated so that the chlorinities (Cl-) are equal to that in the normal sea water of 35‰ in salinity present a nearly linear distribution (Fig. 2). The regression line of these points and coefficient of correlation (c.c., and so on) are as follows: Br-=62.84+0.6680×I-(c.c.=0.9590) The brines from the younger sediments in the Philippines present the similar relationships between both recalculated Br- and I- contents (Fig. 3). The younger sedimentary basins in the Philippines belong also to the lower geothermal heat flow region. However, the authors prefer to recognize two populations and two exceptions in the points on Fig. 3. The regression lines on these two populations and their coefficients of correlation are as follows: Br-=68.27+0.9004×I-(c.c.=0.8856) Br-==49.54+0.9240×I-(c.c.=0.9562) On the other hand, the points excluding only one on the Br--I- diagram representing recalculated Br- and I- contents of some brines from some oil and gas fields in the Sea of Japan side of northeast Honshu are distributed on the upper side of a nearly straight line representing recalculated Br- and I-contents of the brines from the Hachimori oil field (Fig. 4). The regression line and its coefficient of correlation representing these Br- and I- contents are as follows: Br-=72.30+0.7790×I-(c.c.=0.9798) The points on the Br- and I- diagram representing recalculated Br- and I- contents of many brines from some gas fields in Niigata prefecture present a similar distribution pattern (Fig. 5). The oil and gas fields in the Sea of Japan side of northeast Honshu including Niigata gas field belong to the higher geothermal heat flow region (Fig. 1) . The brines from the younger sediments in the region of this kind are characterized by these distribution patterns on the Br--I- diagrams. These patterns suggest the contemporaneous or later supply of bromine to the sediments from the deeper zones of the earth.
A computer simulation of a helical flow is carried out in order to investigate performance of mud in the annulus, and to evaluate effect of rotating drill stem on cuttings carrying capacity of mud. Flow properties of mud taken at a drilling site are approximated by a power law model. Helical flow equations for power law model fluid are derived. Cuttings taken at the well site are divided into two classes, i.e. small spherical-shape ones and large disk-shape ones. Helical flow equations and cuttings sedimentation velocity equations are solved at various conditions to evaluate following matters: 1. The effect of rotating drill stem on viscosity distribution, velocity distribution and pressure loss in the annulus. 2. Average cuttings transport velocity under an assumption of uniform distribution of cuttings in the annulus.