How do you find volume of shale?
How do you find volume of shale?
Estimation of shale volume. The volume of shale (Vsh) is best estimated by logging measurements that respond primarily to shale, in particular, gamma ray and spontaneous potential (SP). The most common methods for estimating shale volumes from gamma ray and SP logs are outlined here.
Why is gamma ray log used as a shale indicator?
Gamma-ray scans of core are also taken to reconcile core depths with log depths. In most stratigraphic and petroleum geological applications, the gamma ray log is used as a “shale log,” both to discriminate shales from “clean” formations, and to estimate the relative shale proportions in shaly reservoir units.
Why do we calculate shale volume?
Calculating shale volume is an important thing to do because, it can be useful to calculate the water saturation, if the reservoir has shale within its body (shaly) such as in delta, that reservoir may has higher water saturation because, shale has the ability to bound together with water which will increase the water …
How do you calculate gamma ray logs?
For standard gamma-ray logs, the measured value of gamma-ray radiation is calculated from concentration of uranium in ppm, thorium in ppm, and potassium in weight percent: e.g., GR API = 8 × uranium concentration in ppm + 4 × thorium concentration in ppm + 16 × potassium concentration in weight percent.
How is shale type and distribution from well logs determined?
Shale affects all well logging measurements to some degree. With using well logging data, presence of shale in a formation can be recognized. Besides, shale types, shale volume and effective porosity can be determined either graphically (Cross-plotting) or analytically using Gamma ray spectrum (CGR).
How do you find out the volume of a shape?
Whereas the basic formula for the area of a rectangular shape is length × width, the basic formula for volume is length × width × height.
Why is shale more radioactive than sandstone?
History of gamma ray tools Because clay minerals have large cation exchange capacities, they permanently retain a portion of the radioactive minerals present in trace amounts in their parent igneous micas and feldspars. Thus, shales are usually more radioactive than sedimentary rocks.
What is Archie equation?
Sw = [ (a / Fm)*(Rw / Rt) ](1/n) Sw: water saturation. F: porosity. Rw: formation water resistivity.
What is dispersed shale?
Dispersed shale is composed of clay minerals, fragments or crystals which usually found on grain surface, occupying pore spaces between particles. Dispersed shale will include both detritus and diagenetic clay minerals. One or both of these forms may be present in this type shale.
What do gamma logs measure?
Gamma ray (GR) logs measure the natural radioactivity in formations and can be used for identifying lithologies and for correlating zones. As shale content increases, the gamma ray log response increases because of the concentration of radioactive material in shale.
