What is spontaneous logging?

spontaneous logging is a method of determining the composition of the underground materials into which it is drilled, usually in the field of oil survey. The process of spontaneous logging potential involves recording the electrical voltage of direct current, which exists between water, such as drilling mud, which is drawn on the well and walls of the well itself. This data is often referred to as a protocol with its own potential (LOG SP) and is recording differences in electrical potential in the range of Milivolts between the layer below the surface and the voltage potential of grounding at the top of the drilling site. In addition to surveying oil, the common uses for spontaneous potential logging include the determination of lithology or rock characteristics of the drilled hole in the research of minerals and the quality of groundwater for municipal purposes.

Using spontaneous Potential logging is considered one of the earliest methods in the exploration of drilling for a specifiedThe nature of the underground terrain. It relies on the natural static electric charge that the soil itself holds. This charge is divided into potential scope spaces in porous rock or led with salt -based fluids and a water -based fluid must be introduced into the well to form a native charge that can be directed to the surface. In general, the higher the electrical potential is detected, the more permeable the layer below the surface, but the size of the deflection also depends on the salinity content used by mud, and the extent of water that naturally occurs in underground rocks.

Well logging relies on both properties of drill mud to be ionic nature, or have electrically charged atoms, as well as clay or minerals in VRT for spontaneous potential logging will take place. Ion charge in the drilling mud is used to make the signal back to the surface. The presence of a certain level of clay or minerals in the hole is essential because their crystalline stThe sequence allows the semipermeable structure to be created. This structure prevents the diffusion of ions in the underground layers, so that the state of natural charge is maintained.

While the procedure for performing spontaneous logging can be quite routine, data interpretation can be difficult. This is because under certain drilling conditions, such as underground collectors, where slate, clay and sand beds meet and combine the data interpreted differently. In particular, it is known that the freshwater places produce widely variable values ​​based on certain parts on changes in the type of mud used and its salinity in relation to the groundwater itself. Reading the negative potential of the SP is usually recorded in an oil well survey, but in freshwater wells, the result is usually a positive reading of SP, which indicates the presence of layers of sand. The spontaneous protocol of potential potential may also be zero if the drill and groundwater have the same electrical potential, which may lead to confusion about realThe nature of the fortified terrain.

In oil production, the use of spontaneous logging is more reliable because the process relies on salinity for good values. For fresh water, sodium chloride must be present both in the drilling mud or in the drill, as well as in the water of natural formation, but ideally the salinity of the formation water should be significantly higher. The way of using spontaneous logging in the potential to obtain underground elements is therefore best limited to regions where sand or slate is present, a high content of salinity.