Seiichi Hirakawa

Geothermal Reservoir Simulation for Water Dominant Fractured Reservoir

Geothermal reservoirs in Japan, except Matsukawa, are mostly the water dominated type, and their reservoir scales are comparatively small. Furthermore, since most of the geothermal areas are located near the national parks, environmental regulations prescribed by the government are very strict in Japan. On the other hand, reinjection of disposal water is an inevitable operation for the development of water dominated geothermal reservoirs.

Natural gas treatment and pipeline transportation at well site

This paper presents the numerical models for the estimation of temperature drop in a low temperature separator and pressure drop in a horizontal pipeline. As a basis for both models, the nume-rical models for flash calculations are fully taken into consideration. These models were applied to some field cases. The calculation results were compared with measured results, and reasonable agreement was observed. These models can be utilized for the selection of separator conditions to prevent the generation of hydrate and for the decision of an inside diameter of a horizontal pipeline in designing surface production facilities of natural gas.

Simulation of Transient Pressure Behavior in a Fractured Geothermal Reservoir

This paper presents a numerical model and an electrical model of a fractured reservoir. Pressure drawdown and buildup tests are simulated with these models. The results of the numerical model agree with those of the electrical model. Further study indicates that the effective transmissibility for a fractured reservoir and the storage capacity ratio can be estimated by the transient pressure techniques.

Computer Program on Water Drive Oil Reservoir

The authors present here a computer program (FORTRAN IV) for calculations on eater drive oil reservoir. The program developed in this paper combines the calculations of determining the original oil in place and predicting the reservoir performance, and gives promise of treating a large quantity of these complex calculations with profitable speed and precision. To decide the optimum values of the original oil in place and the water influx in the program, the slope of curves on original oil vs. production time must be calculated, and those values in the case that the absolute value of the slope is minimum will be selected as the optimum value. Successively, the prediction of the field performance is carried out with the optimum values decided.

Residual Magnetism of Sedimentary Rock Sample

Direction and intensity of residual magnetism of rocks measured by Astatic magnetometer, are analyzed with vector analysis method or Fourier series analysis. The former is more popular, however the vector analysis is effective only in the case that curve of residual magnetism is typical sine curve. In another case this method is unsuitable, if the sample has not ideal shape or has magnetic anisotropy. Such samples can be analyzed only approximately by Fourier series expansion. In both cases, it is necessary to measure the curve of residual magnetism as precisely as possible.The relationship between the results of analysis and precision of the measurement is studied in this paper. The authors also studied the cause of magnetic anisotropy of rock samples whose curve of residual magnetism are not sine curves by microscopic observation. The authors used computers for Fourier series analysis and for the correction of results of residual magnetic declination by a successive approximation.

Fluid Flow Behavior through an Oil Reservoir in Secondary Waterfloods

Fluid flow behaviors through the waterflooded reservior of Omonogawa district (block III of zone III) in the Yabase oil field are studied, using the theory of oil production by frontal displacement.

γ-ray Irradiation Effects on Porphyrin Compound

In consideration of the radiation effects on the origin of petroleum, the writers irradiated with γ-ray on Cu chlorophyrin Na salt, which is a primary derivative of chlorophyll(a source material of petroleum).The results are discussed from geochemical point of view. Desaltization of Cu chlorophyrin Na salt by γ-ray irradiation is the first order reaction of radiation dose. A portion of Cu chlorophyrin Na salt transferred to pheoporphyrin, pheocrythrin and a similar of chlorin. Gaseous products consisting of hydrogen, methane, ethylene, ethane, propane and carbondioxide are obtained. The presence of rocks and water has an influence on radiolysis, and the effects are more pronunced than those obtained during irradiation in bulk.From these experimental results, the writers suggest that natural radioactivity from minerals in sedimentary rocks might play an important role for the formation of petroleum.

Effect of Sand Wettability on Some Properties in the Petroleum Reservoir Engineering

The authors investigated on capillary pressure, relative permeability and resistivity using unconsolidated sands which were water-wet or oil-wet. The preferentially water-wet sands were treated so as to make the surface to be preferentially oil-wet. The results are discussed in terms of the effect of changes in wettability on some properties in the petroleum reservoir engineering.

A Laboratory Study on Drilling Mud Resistivity and Mud Filtrate Resistivity

Drilling mud resistivity and mud filtrate resistivity were measured, using the synthetic muds: those are clay base muds with additives (salt•humic acids•CMC•barite) and oil emulsion muds with additives. From the standpoint of electric log interpretation, dependence of these resistivities on temperature (15°C_??_80°C) and different mud additives is discussed, and the relationship between mud resistivity and mud filtrate resistivity investigated.

Evauation of Gas-in-place and Production Behaviors in Natural Gas Resevoir of Free Gas Type

In this paper are discussed the evaluation of gas-in-place and production behaviors in natural gas reservoir of free gas type, and the properties of gas reservoir fluids such as gas converesion factor, solubility and water formation volume factor. These discussion are chiefly based upon the calculated results which were computed under pre-determined conditions, In these calcu-lation are involved the encroachment effect of water into the gas reservoir and the evolution effect of natural gas from liquid phase within the reservoir.