Gamma ray shale index
18 Nov 2015 Well-logging Lab No. 4 - Calculation of Gamma Ray Index IGR for Shale Volume Calculation - Free download as PDF File (.pdf), Text File (.txt) 7 Jan 2018 The volume of shale expressed as a decimal fraction or percentage is called Vshales. Calculation of the Gamma Ray Index (IGR ) is the first 4 Jan 2018 The suite of logs should include gamma ray, dipole sonic, deep resistivity, The estimation of the shale volume in the zone of interest can be as vitrinite reflectance, thermal alteration index (Tmax) or Rock-Eval pyrolysis. The so-called factor index is defined analogously with natural gamma ray index for describing a linear relationship between one special factor and shale content. In some black shales, the gamma-ray log also responds to uranium associated with organic matter. Glacial sediments rich in clay, such as till or lacustrine mud, Shale. Shale. Sand. Hydrocarbon. Brine. Brine. Oil. Gas. Figure 1. A basic log. today's basic suite of logging measurements includes a gamma ray (GR) curve index (HI). Neutron porosity tools measure the HI, which is then converted. 4 Jul 2019 Vsh = volume of shale. IGR = gamma ray index. 2.3.3. Porosity. The computation of porosity was done in stages, the first involved the use of the
The section is nearly a thousand feet in length and the gamma-ray scale has been expanded to 400 API units to accommodate the higher radioactive black shales. The limestones have low radioactivity, with a value of about 20 API units. A representative value for the gray shales is in the neighborhood of 120 API units.
Shale is usually more radioactive than sand or carbonate, gamma ray log can be used to calculate volume of shale in porous reservoirs. The volume of shale expressed as a decimal fraction or percentage is called V shale. Calculation of the gamma ray index is the first step needed to determine the volume of shale from gamma ray log. SHALE Volume FROM Gamma Ray LOGS. The two most common shale indicating logs are the gamma ray (GR) and spontaneous potential (SP) logs. The units of measurement for GR are API units or counts per second, and for SP are millivolts. The equation (1) shown below defines an IGR shaliness index as a function of the GR gamma ray log signal: It only needs to record the response of the gamma ray log for a nearby known shale body and a nearby known clean rock. Gamma Ray Index - IGR Shale Volume - GR Gamma ray index (IGR) is calculated from the well logging tool that has its same name. This index takes into account minimum gamma ray (GR) value (cleanest zone), the maximum GR value (most shaly zone), and the value of the study area or depth. The section is nearly a thousand feet in length and the gamma-ray scale has been expanded to 400 API units to accommodate the higher radioactive black shales. The limestones have low radioactivity, with a value of about 20 API units. A representative value for the gray shales is in the neighborhood of 120 API units. Even better, the difference does not depend upon Gamma Ray, so it provides a GR independent estimator: Clay minerals like kaolinite, chlorite, illite, and montmorillonite, have a high hydrogen index.
Calculation of the gamma ray index is the first step needed to determine the volume of shale from a gamma ray log (the following formula from Schlumberger,
where IGR is the gamma ray index, Vsh is the shale volume, GRlog is the gamma ray reading, GRmax is the maximum gamma ray reading, and GRmin is the minimum gamma ray reading. 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 The relationship between gamma ray index, Igr and shale content, Vsh, in shaly sands is a quantitative indication for shale content. It is used in well logging for oil and gas.
16 Feb 2018 Keywords: Gamma spectrometry, radiometric indices, radionuclides concentrations, shale rocks Knowing the radiation levels and radionuclide distributions in the environment is important for assessing the effects of
7 Jan 2018 The volume of shale expressed as a decimal fraction or percentage is called Vshales. Calculation of the Gamma Ray Index (IGR ) is the first
Gamma Ray Index - IGR Shale Volume - GR Gamma ray index (IGR) is calculated from the well logging tool that has its same name. This index takes into account minimum gamma ray (GR) value (cleanest zone), the maximum GR value (most shaly zone), and the value of the study area or depth.
Shale Volume from Gamma Ray Log Models. Learn basics, borehole corrections, normalization, spectral gamma ray methods, non-linear Clavier corrections, Background. • The Gamma Ray log is a continuous measurement of Principal isotopes emitting radiation are Potassium-40, Calculate shale index, IRA , by. 18 Nov 2015 Well-logging Lab No. 4 - Calculation of Gamma Ray Index IGR for Shale Volume Calculation - Free download as PDF File (.pdf), Text File (.txt) 7 Jan 2018 The volume of shale expressed as a decimal fraction or percentage is called Vshales. Calculation of the Gamma Ray Index (IGR ) is the first 4 Jan 2018 The suite of logs should include gamma ray, dipole sonic, deep resistivity, The estimation of the shale volume in the zone of interest can be as vitrinite reflectance, thermal alteration index (Tmax) or Rock-Eval pyrolysis. The so-called factor index is defined analogously with natural gamma ray index for describing a linear relationship between one special factor and shale content. In some black shales, the gamma-ray log also responds to uranium associated with organic matter. Glacial sediments rich in clay, such as till or lacustrine mud,
hydrogen index (HI), is commonly expressed in spontaneous gamma ray, neutron, and density) using shale, matrix-hydrogen, and neutron lithology units . In areas with low shale volume (i.e. areas with Gamma Ray less than. 50 API); minerals such as montmorillonite are widely observed. Consequently a direct The volume of shale was calculated from gamma ray index and the values range from 11% to 17% indicating that the fraction of shale in the reservoirs is quite low. chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with 2), and is overlain by the marine shales of the maturity index). 20 Jan 2017 saturation in the shaly formation. Different shale indicator methods are used in practice, which are based on the estimation of gamma ray index Calculate the gamma ray index and shale volume if the rocks at depth 3,500 ft and 7,500 ft. Q.9. Sonic log reading. Calculate porosity. fts t fts t.