There have been carried out many studies on the C/N ratio of recent sediments. but few studies on ancient sediments. The relationship of carbon and nitrogen for nine-teen samples of marine kerogen shales of Tertiary age in Japan was examined. consequently carbon and nitrogen showed an approximatly logarithmic linear functional relation as have been showed in recent sediments by G. ARRHENIUS. The ratio C/N from muddy siltstone group of “Onnagawa formation” was found to be higher, the mean being 27, than 14 of Trask's mean value from past sediments, and each sample of this group indicated that there is litte difference in nitrogen concentration but higher in carbon concentration in comparison with some of the other examined samples. The present auther thinks that this high ratio C/N wouldbe based on elemental carbon concentration in total organic carbon of each sample of that group. From the above mentioned point of view, a new attempt waa propsed by the present auther, to discriminate the carbon in highly condensed form (nearly elemental organic carbon, namely charcol, graphite, coal) from the total organic carbon of the sedimentary rock.
Sample solutions of the diffusivity equation for linear flow are derived in this paper. These solutions can be used to investigate the flow problems qualitatively in oil and gas reservoir. An example is presented to show the application of the equation to predictions of production performance in natural gas reservoir of completely dissolved-in-water type.
Results of a study on the invasion of mud fluid into free gas zone tested by the use of artificial consolidated sands are described in this paper. Some of the results obtained are as follows: (1) as mud pressure increases the speed of invasion increases, (2) barite mixed in mud fluid affects a little on the speed of invasion, (3) CMC in mud fluid decreases the speed of invasion, and (4) as the degree of reduction of gas permeability of sands by mud invasion, it is conspicuously smaller on the cores of originally lower permeability and on the cores of which mud invaded longer time.
Brine from Niigata natural gas field has the abnormal characteristics in the chemical composition of dissolved material and in the isotopic composition of hydrogen of water molecule. Na/Cl of Niigata brine has extraordinarily smaller value than that of sea water and other brines. The deuterium content determined by T. Chitani and Y. Horibe has abnormally decome impoverished in Niigata brine. The ordinary brines have a deuterium content that is comparable to that of sea water. These facts mean that original Niigata brine has been contaminated by much choride- and much protium-bearing water during geological ages.