Figuring out cuttings lag time and receiving of core cuttings from core barrel during drilling of formation.

Most of us use oil, and it is difficult to imagine the modern world without oil,but oil and gas are not, easy to find and get out of the earth. It is of course wecannot see the oil which is trapped deep, down in the ground. Geologists muststudy rocks carefully, and when they know rocks in a certain place, containing oilor gas, drilling processes will then take place. Oil and gas are obviously not rocks,but they are, derived from rocks, like sedimentary rocks.Petroleum occurs in the pores of sedimentary rocks, the most common are,sandstones, limestone and dolomites, which may contain porosity and permeabilityfilled with oil, gas and water and they can act as reservoir rocks. Most drilling oilcompanies require a mudlogging unit on their wells, to provide identification andevaluation, of oil and gas bearing formations, during drilling operations. The main,source of geologic data are the cuttings of rocks produced in the process ofdrilling a well, whears core cuttings are a cylindrical rock sample of differentdiameters, used to understand, the subsurface conditions, like rock type, porefluids and detailed reservoir characteristics. In rotary drilling, the drilling fluid ispumped, from the surface, down inside the drill string, and through vents in the,drilling bit at the bottom hole, this fluid returns, back to the surface through theannulus between, the drill string and the walls of the hole carrying well cuttingsfrom the bottom hole up to the surface, were they are collected. There is always atime Lag between when the formation is drilled and when cuttings returns back tothe surface, this time is called "lag time". This time used is to ascertain the truerepresentative depth from which cuttings come, controlled by the slip velocity ofdrilling fluid. The objective of this study is to calculate and figure out the lag timerequired for well cuttings to reach from the bottom of the well up to the surfaceand receiving core cutting from core barrel during drilling formation whichproduce cuttings. A case study for the well (f- 22) drilled to a total depth of 12000feet, and a core cuttings are taken in this well through the Gargaf formationrepresents a reservoir rock in this well, and figuring out the lag time of wellcuttings form the bottom of the well up to surface