Noriaki Watanabe

A numerical model incorporating experimentally determined fracture surface geometries and fracture permeability is proposed for characterizing aperture structures and fluid flow through rock fractures under confining pressures. The model was applied to artificially created granite tensile fractures with varying shear displacements (0–10 mm) and confining pressures (10–100 MPa). The findings of the study were consistent with those obtained previously, which characterized experimentally determined

Shear (Mode II) fractures with shear displacements of 1 and 5 mm were generated by direct shear on granite under normal stresses of 1, 20, and 60 MPa. Fracture surface mapping showed that the surface roughnesses of the shear fractures decreased with increasing shear displacement and normal stress and were smaller than those of tensile fractures reported in our previous study. Fluid flow experiments on the shear fractures provided fracture permeabilities at a wide range of confining pressures of

Abstract Hydraulic fracturing experiments were conducted at 200–450°C by injecting water into cylindrical granite samples containing a borehole at an initial effective confining pressure of 40 MPa. Intensive fracturing was observed at all temperatures, but the fracturing characteristics varied with temperature, perhaps due to differences in the water viscosity. At the lowest considered temperature (200°C), fewer fractures propagated linearly from the borehole, and the breakdown pressure was twic

Abstract Appropriate relative permeability curves for two‐phase flows through subsurface fractures remain unclear. We have conducted decane‐water and nitrogen‐water two‐phase flow experiments and simulations on real variable‐aperture fractures in rocks under confining stress. Experiments have been conducted on fractures for different combinations of rock type (granite or limestone), wettability (contact angle of water: 0° or 90°), and intrinsic fracture permeability (10 −11 m 2 or 10 −10 m 2 ) u

Improving geothermal systems through hydraulic stimulation to create highly permeable fractured rocks can induce seismicity. Therefore, the technique must be applied at a moderate intensity; this has led to concerns of insufficient permeability enhancement. Adding chemical stimulation can mitigate these issues, but traditional methods using strong mineral acids have challenges in terms of achieving mineral dissolution over long distances and highly variable fluid chemistry. Here, we demonstrate

Superhot geothermal environments (above ca. 400 °C) represent a new geothermal energy frontier. However, the networks of permeable fractures capable of storing and transmitting fluids are likely to be absent in the continental granitic crust. Here we report the first-ever experimental results for well stimulation involving the application of low-viscosity water to granite at temperatures ≥400 °C under true triaxial stress. This work demonstrates the formation of a network of permeable microfract

The use of the simian immunodeficiency virus (SIV) macaque model for assessing human immunodeficiency virus vaccine strategies will be facilitated by the characterization of predominant SIV cytotoxic T-lymphocyte (CTL) epitopes and their restricting major histocompatibility complex (MHC) class I molecules in macaque species. We now define a rhesus monkey SIVmac CTL epitope in the third hypervariable region of the envelope glycoprotein of the virus. This epitope, YNLTMKCR, contains the first two

Summary The present study focuses on the feasibility of a precise 3D numerical modeling coupled with X-ray computed tomography (CT), which enables simple analysis of heterogeneous fracture flows within reservoir core samples, as well as the measurement of porosity and permeability. A numerical modeling was developed and applied to two fractured granite core samples. One of the samples had an artificial single fracture (sample dimensions: 100 mm in diameter, 150 mm in length), and the other had n