عمليات جس الآبار النفطيه أثناء الحفر (LWD) وعلاقة معدتها بمعدات القياس أثناء الحفر (MWD) تابعونا

Well Logging Operations and Their Relationship to Measurements During Drilling (Logging While Drilling) # Well Logging and Its Relationship to MWD Well Logging Operations: Upon completion of drilling a specific geological section and before casing installation, well logging operations are conducted. These operations involve lowering electrical, electronic, and acoustic instruments to record the properties of the geological section's rocks and the fluids it contains, as well as the well conditions from the bottom of the well to the last casing. There are some types of logs that can be used for casing wells as well. The information obtained from these logs is considered the best way to evaluate geological formations in terms of porosity, permeability, hydrocarbon indicators, shale content, and other properties. The most important types of logs are: Density Log (FDC): This log measures the density of rocks, which has an inverse relationship with porosity. The higher the porosity, the lower the density. Anhydrite is one of the densest rocks, while porous limestone and porous dolomite are among the least dense. Neutron Log (CNL): This log also measures porosity, but indirectly. It measures the number of hydrogen atoms in the rock, which is related to porosity, by using a stream of neutrons that collide with the hydrogen in the rock. Each hydrogen atom in the rock traps a neutron, and thus, by knowing the number of neutrons trapped, we can estimate the number of hydrogen atoms. The hydrogen atoms in the rock, and consequently the porosity of that rock. *Gamma ray probe: (x-ray) Gamma ray is considered one of the most important probes because it indicates the extent to which the rock contains radioactive materials (shale) or its purity. Rocks differ in their gamma ray emission according to the degree to which they contain shale and other clay minerals. Anhydrite and limestone are considered purity compared to shale, clay, and silt, which are considered to contain radioactive materials. Gamma ray probes are useful for geological comparisons to determine stratigraphic sequences and for stabilizing drilling depths during perforation. Gamma radiation is recorded in APT units, ranging from 0 to 100. Resistivity logs measure the resistance of rocks to the flow of electric current. The fluids present in rock pores (oil, gas, and water) have different resistances to electric current. Oil and gas are more resistant than water, and fresh water is more resistant than salt water. There are three types of resistivity logs. Deep Laterolog (Long Laterolog) Shallow Laterolog (Shallow Laterolog) Micro Resistivity (Micro Resistivity) The benefit of resistivity logs is to identify geological sections containing hydrocarbon evidence, which are areas of porous rock with high resistivity. They also help us determine the level of oil-water contact, where we observe a gradual decrease in resistivity values ​​in a geological section characterized by stable and homogeneous porosity. Resistivity logs can also (indirectly) indicate the rock's hardness. Sonic Log (Sonic Log): This log helps us estimate the primary porosity of a rock, unaffected by subsequent processes such as fracturing and faulting. This log relies on the principle that the speed of sound is higher in hard, dense, non-porous rocks than in porous, less porous rocks. A sound wave is generated and directed at the rock, and its reception is measured at another location. By calculating the time it takes for the wave to travel to and from the rock, the rock's porosity can be indirectly estimated. The acoustic probe is also useful in predicting abnormal pressures, especially if the geological section contains shale. Shale has a specific pressure gradient with increasing depth, and when this gradient is disrupted, we can predict that we have entered an area of ​​abnormal pressure. The acoustic probe is considered one of the best probes for identifying rock salt layers. *Wellbore Diameter Log: This log consists of several arms, either two or four, that open at a specific diameter corresponding to the wellbore diameter at that point. The size of the opening in this arm is converted into an electrical signal, which is recorded on logging paper as a line representing the wellbore diameter at that depth. The wellbore diameter log is useful in identifying areas of collapse or salt dissolution, thus aiding in calculating the amount of cement needed to line the well. It also helps in identifying areas of constriction for reaming before casing installation. *Formation Slope Log: This log measures microresistivity at varying distances from the wellbore wall for the same formation. If the formation is inclined, as is the case at the edges of a geological structure, this is expressed by all four logs recording the same resistance but with slight differences in depth. The first log penetrates the formation to a greater depth than the second, and the second to a greater depth than the ...