In exploration and drilling for oil, microgravity surveys are used to map subtle regional density variations that can be related to oil and gas reservoirs. The technique is based on accurately measuring tiny variations in the gravity field of an area of interest. By analyzing the gravity field data, regions of anomalous density related to oil and gas reservoirs can be identified, providing an invaluable tool in exploration and drilling efforts.
Microgravity surveys measure changes in gravity caused by variations in subsurface density that are related to oil and gas reservoirs, enabling exploration crews to identify areas of interest below the surface that may contain significant concentrations of hydrocarbons. Microgravity surveys are typically conducted prior to, or in conjunction with, seismic surveys in order to improve our understanding of the subsurface density of a region.
When conducting a microgravity survey, gravity observations are typically made at established points along the survey line. The data collected at each point is then processed using a gravity system consisting of a spacecraft, computers, and software. This system is capable of calculating the local value of gravity at each point, as well as its total deviation from the average value of gravity in the region. These deviations are used to identify areas of anomalous density which are often related to oil and gas reservoirs.
The microgravity survey procedure also includes several other steps that are necessary to accurately collect and interpret the data. First, the survey area is clearly outlined and the exact positions of the survey points in the region are determined. Secondly, an accurate gravity baseline value is established for the region. This baseline value is typically based on gravity observations that have been taken across several adjacent survey points. This ensures that a reliable and consistent gravity baseline can be established for the region in question. Thirdly, the exact elevation of each survey point is determined and the difference in elevation and gravity between the points is recorded. Fourthly, the measured gravity at each point is then corrected for elevation, atmosphere, and tide to obtain the true gravity value. Finally, a statistical analysis is performed on the corrected gravity data to determine areas of anomalous density that are related to oil and gas reservoirs.
Microgravity surveys can provide a considerable advantage in exploration and drilling operations. The ability to accurately and efficiently map subsurface structures related to oil and gas reservoirs can save considerable time and energy, and can potentially result in a more accurate picture of the subsurface of an area of interest. Additionally, a microgravity survey can help to identify geological features that may not be revealed through more conventional exploration techniques.
