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* [http://www.searchanddiscovery.com/documents/nanz/images/23.htm Gamma-ray and resistivity response]

==Outcrop gamma-ray logging==

...P_{\text{c system2}} \left ( \frac{\gamma \cos \Theta \text{ of system1}}{\gamma \cos \Theta \text{ of system2}} \right )</math> ...c res}} = P_{\text{c lab}} \left ( \frac{\gamma \cos \Theta_{\text{res}}}{\gamma \cos \Theta_{\text{lab}}} \right )</math>

| rowspan = 2 | Correlation || [[Basic open hole tools#Gamma ray|Gamma ray]] | Spectral gamma ray

...open hole tools#Resistivity|electric]], [[Basic open hole tools#Gamma ray|gamma ray]], etc.). It is important to realize that a sonic log never goes to the

...e measured using density sonic, neutron, [[Basic open hole tools#Gamma ray|gamma ray]], and [[Basic open hole tools#Resistivity|resistivity logs]]. The tabl | Gamma ray (GR) or uranium (U) || High || High GR caused by U; can be linear with

...nts. (right) Density values measured by the BHGM (left line) and the gamma-gamma tools (right line). Copyright: Rasmussen;<ref name=Rasmussen>Rasmussen, N. ...w is caused by a remote higher [[porosity]] zone not detected by the gamma-gamma density log. The broader difference anomaly observed over the length of the

:<math>(\rho_{\rm w} - \rho_{\rm h}) \mbox{g} h = \frac{2\gamma \cos \theta}R</math> :<math>h = \frac{\left(\displaystyle\frac{2\gamma \cos \theta} R \right)}{(\rho_{\rm w} - \rho_{\rm h})\mbox{g}}</math>

| [[Basic open hole tools#Gamma ray|Gamma ray]] || 6 || 20 || √ || √ || √ || √ || √ || √ || – || – || | Spectral [[Basic open hole tools#Gamma Ray|GR]] || 6 || 20 || √ || √ || √ || NR || √ || √ || NR || – |

...can include standard measurements of the formation (electric logs such as gamma ray, resistivity, or porosity), drilling parameters (e.g., downhole torque,

...while drilling (MWD) technology provides downhole evaluation of formation gamma ray, resistivity, and [[porosity]] while drilling is in progress. Mechanica ...servoir evaluation in the past 10 years. [[Basic open hole tools#Gammy ray|Gamma ray]], resistivity, and porosity logs obtained during drilling are commonly

...y between 6330 and 6370 ft is caused by porosity not detected by the gamma-gamma [[density log]]. The broader difference anomaly observed over the length of ...r poor volume sampling. However, the broad departure of the BHGM and gamma-gamma logs over the depth range of the logged section is typical of a structural

| Gamma Ray (GR) || Lithology interpretation, shale volume calculation, calculate c [[File:Well_Log_Analysis_Fig-3.png|thumb|300px|Figure 3-The use of gamma ray log to determine the lithology.<ref>Railsback, 2011, Characteristics of

| Gamma-gamma log || 8 || 20 || 17 || 0.5

:<math>\mbox{P}_{\rm c} = \frac{2\gamma \cos \Theta}{\mbox{r}}</math> :<math>\mbox{r} = \frac{2\gamma \cos \Theta}{\mbox{P}_{\rm c}}</math>

| Gamma ray ...ces make use of three different physical phenomena: spontaneous potential, gamma rays, and photoelectric effect. Table 2 shows the resolution and applicatio

...wise to select the gamma ray from the induction tool as the base log. The gamma ray from the density curve and all curves recorded with the density are the :A core gamma ray can be a valuable aid in establishing depth correlations between core a

...source, counts the number of returning gamma rays. The number of returning gamma rays is an indicator of formation bulk density. The litho-density tool (LDT

* [[Basic open hole tools#Gamma ray|Gamma ray]] ==Gamma ray logs==

...otential (SP)]]. The most common methods for estimating shale volumes from gamma ray and SP logs are outlined here. Other measurements can be used under spe ===Shale volume from gamma ray===

* [[Basic open hole tools#Gamma ray|Gamma-ray]] log changes in response to increased uranium concentration at exposur

...tions and order of logging runs (usually [[Basic open hole tools#Gamma ray|gamma ray]], deep resistivity, [[porosity]], sonic, pad-type resistivity, [[dipme

...on_fig2.png|300px|thumb|{{figure number|2}}Example of correlating ROP with gamma ray curves.]] ...can be used to correlate to nearby wells. This is done by comparing ROP to gamma ray or SP curves ([[:file:rate-of-penetration_fig2.png|Figure 2]]). This co

...Such an instrument has either one or two [[Basic open hole tools#Gamma ray|gamma]] ray detectors spaced below the ejector. By various techniques, the operat ...ng_fig3.png|Figure 3]]. The tool is stationary during such a test, and the gamma count rate is recorded at the surface. In [[:file:production-logging_fig3.p

...h in calcareous nannoplankton and foraminiferal fossils and having maximum gamma-ray values are interpreted to correlate with condensed depositional interva ...n of stacked depositional sequences. The [[Basic open hole tools#Gamma ray|gamma-ray]] log display provides a measure of sediment type, with curve deflectio

:<math>\mbox{P}_{\rm d} = \frac{(2\gamma \cos \theta)}{\mbox{R}}</math>

* [[Spectral gamma ray]]

...es \mbox{l} \times \sin \mbox{Q} \times (\rho_{\rm w} - \rho_{\rm hc}) > 2\gamma</math>

...ok lithology from logs]]). Commonly, the [[Basic open hole tools#Gamma ray|gamma ray]] log provides the most distinctive log signature for individual facies

...te]]s, commonly have the highest gamma ray activity. However, the level of gamma ray activity in some carbonates ([[dolostones]] in particular) is not relat

...hole tools#Spontaneous potential|SP]] or [[Basic open hole tools#Gamma ray|gamma ray]] trace and the right track is a resistivity trace. (From Slatt et al.< ...hole tools#Spontaneous potential|SP]] or [[Basic open hole tools#Gamma ray|gamma ray]] log and one [[Basic open hole tools#Resistivity|resistivity log]] are

...on well-log traces) occurring above successive, laterally persistent high gamma-ray (or minimum spontaneous potential [SP]) shale markers that are interpre ...jpg|Figure 6]]). Interbedded mudstones displaying thin, spiky, and serrate gamma-ray and SP log motifs accumulated in the interaxial areas where intermitten

| [[Core gamma scan]] | [[Basic open hole tools#Gamma ray|Gamma ray]] log

...crepancies in the core log. Comparison of the core gamma with the wireline gamma log allows the core-to-log shift to be determined. This is important for ma | Gamma ray log || Measures the natural gamma-ray response of the rock || Well-log correlation, lithology identification;

| Gamma ray || May decrease slightly || May increase slightly

:<math>\mbox{P}_{\rm d} = \frac{-2\gamma \cos \theta}{\mbox{r}}</math>

...r depth control and can be of great assistance only if there is sufficient gamma ray activity in the core to provide precise boundaries. Should closely spac

...tones containing potassium feldspars or thorium-bearing clays. The natural gamma ray spectra, Pe, density, and neutron expanded response equations can be co * [[Spectral gamma ray]]

...Project (EGSP), there is a strong relationship between higher-than-normal gamma ray response and total gas content in the black, organic-rich Marcellus Sha ...ral length of 20,060 ft (Boyer, 2021, Gough, 2020). The organic-rich, high gamma ray portion of the Marcellus Shale is thickest in southwestern and north-ce

...tential|spontaneous potential (SP)]] and [[Basic open hole tools#Gamma ray|gamma ray]] curves. Grain size is determined by comparison with a chart made of s

...he unconformity. The unconformity may be recognized in well logs by a high gamma ray count due to glauconite or uranium if the unconformity is covered by ma

...cording of the raw dipmeter data showing the orientation curves, calipers, gamma ray, and correlation curves from a six-arm tool. Note that the curves are r ...g4.png|Figure 4]] is a standard arrow plot that also carries a correlation gamma ray curve and maximum and minimum caliper values. On the right-hand side is

...y value within the scale of measurement. [[Basic open hole tools#Gamma ray|Gamma ray]] log values, the porosity or permeability of a rock, or the subsea ele

...d logged. The tools can be precisely positioned in zones of interest using gamma logs or SP logs as guides. Percussion or rotary drilled samples provide sma

...g shale interval, or called “high quality shale”, is characterized by high gamma ray (GR), high uranium (U), high acoustic (AC) and low density (DEN) (Fig.

...s of greater than 1–2%, depending on the degree of [[thermal maturation]]. Gamma-ray values in some wells have been adjusted according to [[offset]] shale b

...n they provide: (1) lithology indicators—[[Basic open hole tools#Gamma ray|gamma ray]], [[Basic open hole tools#Sonic|sonic]], [[Basic open hole tools#Densi

...metrics),<ref name=ch18r11>Curry, W., H., III, 1984, Evaluation of surface gamma radiation surveys for petroleum exploration in the deep Powder River basin,

...extreme variations in thickness. Thicknesses ocassionally exceed 100 m. On gamma-ray logs, the M is blocky, with a sharp base and top. On seismic data and i

...aubouef<ref name=BB2004 />). The lower section shows a series of idealized gamma ray logs.]] ...eprinted with permission from, and &copy; by, the Geological Society. GR = Gamma Ray; RFTtrade = Repeat Formation Tester; UKCF = Upper Kimmeridge Clay Forma

...ssed to produce total intensity [[contour]] maps (with intervals down to 1 gamma and occasionally less) and digital data files. The processing often include

:<math>\mbox{h} = \frac{0.670 \times \gamma \cos \theta}{\mbox{R}_{\rm bt}(\rho_{\rm w} - \rho_{\rm h})}</math>

...t al.<ref name=Hamiltonetal_2002 />). SP = spontaneous potential log; GR = gamma-ray log.]] ...etin, v. 56, no. 8, p. 1541–1544.</ref> For each well, a paper copy of the gamma-ray log is trimmed to the top and base of the reservoir unit of interest an

.... There are various type of wireline logging: radioactive log, consists of Gamma Ray, Neutron, and Density; electric log, consists of SP and resistivity; ac

...here Sand A (clean sandstone) and Sand B (clayey sandstone as indicated by gamma ray log) have different density and wave velocities compared to the claysto

...10.jpg|{{Figure number|10}}Type log for Wattenberg Field. Curves shown are gamma ray, spontaneous potential, resistivity, and neutron/density. Black bar in ...0.jpg|{{Figure number|20}}(A) Type log Codell Sandstone, Wattenberg Field. Gamma ray, spontaneous potential, resistivity, neutron, and density curves shown.

...ined on the electric logs by repetition or omission of parts of the SP and gamma ray signatures compared to a reference well that is believed to show an unf

...particularly in southwestern Pennsylvania and northern West Virginia, peak gamma-ray counts in excess of 300 to 400 API are not uncommon and reflect the gen ...als. G/C3 = matrix density ρmatrix (in grams per cubic centimeter); GAPI = gamma-ray API units; SEM = scanning electron microscope; TVD = true vertical dept

...ace using petrophysical logs (gamma ray, density, sonic etc; Fig. 15). The Gamma ray (GR) log response of dolostone / dolomite-rich carbonates can be lower

...ate of penetration (ROP), Weight on bit (WOB), Near-bit inclination (NBI), Gamma Ray (GR) and few other parameters. The sonde GR instrument is often placed

|Askeladden Gamma

:<math>\Delta \gamma \times g \times \sin{\alpha}</math>

::<math>\sigma_h = k \sigma_v = k \gamma z</math>

| Magnitude of extension (''&gamma;'', 0-1) || 0.1 || 0.64 || 0.9

...ell spacing is large<br>Requires modern log suite ([[Basic open hole tools#Gamma ray|GR]], [[Basic open hole tools#Density|density]], [[Basic open hole tool

...ine) occurs as represented on the southern half of cross section A-A’. (C) Gamma Ray–Density-Neutron log across the Wolfcamp C showing a representative sa ...lfcamp in the southern Delaware Basin. (A) Eagle Oil & Gas Co., Sheldon #1 Gamma Ray, Density–Neutron log. The drop in Density–Neutron circled red corre

...al lags contain abundant mudclasts, they can be mistaken for shales on the gamma-ray log. Caution should be taken where a shale-like wireline log response i

...Prudhoe Bay field, Alaska (from Tye et al.<ref name=Tyeetal_1999 />). GR = gamma ray.]]

...gure12.jpeg|Figure 12]]. Tracks (from left to right): stratigraphic Units; gamma ray; thickness reference with dotted lines every 50 m; Passey filter; TOC (