Density logging

Density logging

Well logging

Gamma ray logging Spontaneous potential logging Resistivity logging Density logging Sonic logging Caliper logging Mud logging LWD/MWD v · well logging tool determining rock bulk density along a wellbore. This is the overall density of a rock including solid matrix and the fluid enclosed in pores. Geologically, bulk density is a function of the density of the minerals forming a rock (i.e. matrix) and the enclosed volume of free fluids (porosity). General tool design Modern density logging tools, generally shares the same design principles independent of manufacturer. Tool consist of housing with electronics catridges and a sonde part. Sonde part has a measuring pad, where radiactive source (CS-137 nowadays) is inserted and a number of detectors (Long Space, Short Space, and a "Backscattering" detector). Measuring pad is connected with a hydraulically operated caliper arm, which is used to measure borehole diameter, and on the same time apply pressure to the pad to ensure it's contact with the borehole. Density measurements are extremely sensitive to shape of the borehole - readings in large washouts are irrelevant due to very shallow depth of investigation of density tools. Principle A radioactive source applied to the hole wall emits medium-energy gamma rays into the formation so these gamma rays may be thought of as high velocity particles which collide with the electrons in the formation. At each collision the gamma ray loses some of its energy to the electron, and then continues with diminished energy. This type of interaction is known as Compton scattering. The scattered gamma rays reaching the detector, at the fixed station from the source, are counted as an indication of formation density. The number of Compton scattering collisions is related directly to the number of the electron density of the formation. Consequently, the electron density determines the response of the density tool. Electron density is related through equation $\rho \dot{\epsilon}= \frac{2\rho B \sum Z_{1i}}{M}$ where $\textstyle \sum Z_{1i}$ is the atomic numbers of all the atoms making up the molecules in the compound, and $M$ is them molecular weight of the compound. Inferring porosity from bulk density Assuming that the measured bulk density ( $ρ bulk$ ) only depends on matrix density ( $ρ matrix$ ) and fluid density ( $ρ fluid$ ), and that these values are known along the wellbore, porosity ( $ϕ$ ) can be inferred by the formula $\phi = \frac{\rho_\text{matrix} - \rho_\text{bulk}}{\rho_\text{matrix}-\rho_\text{fluid}}$ Common values of matrix density $ρ matrix$ (in g/cm³) are: Quartz sand - 2.65 Limestone - 2.71 Dolomite - 2.87 Density of clay minerals is highly variable, and depends on depositional environment, overburden pressure, type of clay mineral and many other factors. It can vary from 2.1 (Montmorillonite) to 2.76 (Chlorite). A fluid bulk density $ρ fluid$ of 1 g/cm³ is appropriate where the water is fresh; highly saline water has a slightly higher density. For flushed gas or oil reservoirs, even lower $ρ fluid$ values should be assumed depending on the hydrocarbon density and residual saturation. In some applications hydrocarbons are indicated by the presence of abnormally high log porosities. Categories: Well logging Petroleum Petroleum stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем решить контрольную работу Stumpy Tower Italian Heritage and Culture Month Committee of New York Look at other dictionaries: Logging while drilling — (LWD) is a technique of measuring geologic formation properties in real time while drilling an oil well.DescriptionLogging while drilling, along with measurement while drilling systems provide wellbore directional surveys, petrophysical well logs … Wikipedia density log — n, = gamma gamma log measures electron density within lithologic units which is related to their bulk density. The wireline tool records the intensity of gamma radiation (in counts per second) from a nuclear source within the tool after it has… … Coke&Coal Terminology Well logging — Gamma ray logging Spontaneous potential logging Resistivity logging Density logging Sonic logging Caliper logging Mud logging LWD/MWD v · … Wikipedia Mud logging — Mud log in process. Well logging Gamma ray logging Spontaneous potential logging Resistivity logging Density logging … Wikipedia Whitestone Logging Camp, Alaska — Infobox Settlement official name = Whitestone Logging Camp, Alaska settlement type = CDP nickname = motto = imagesize = image caption = image mapsize = 250px map caption = Location of Whitestone Logging Camp, Alaska mapsize1 = map caption1 =… … Wikipedia well logging — the process or technique of recording a well log. * * * ▪ mining field technique used in mineral exploration to analyze the geologic formations penetrated by a drill hole. If the hole has been drilled by using coring techniques, the core… … Universalium Crosshole sonic logging — (CSL) is a method to verify the structural integrity of drilled shafts and other concrete piles. The CSL method is considered to be more accurate than sonic echo testing in the determination of structural soundness of concrete within the drilled… … Wikipedia Formation evaluation — In petroleum exploration and development, formation evaluation is used to determine the ability of a borehole to produce petroleum. Essentially, it is the process of recognizing a commercial well when you drill one .Modern rotary drilling usually … Wikipedia Gas porosity — Determining the true porosity of a gas filled formation has always been a problem. While gas is a hydrocarbon, similar to oil, the physical properties of the fluids are very different, making it very hard to correctly quantify the total amount of … Wikipedia Measurement while drilling — Well logging Gamma ray logging Spontaneous potential logging Resistivity logging Density logging Sonic logging Caliper logging Mud logging LWD/MWD v · … Wikipedia 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”