Formation pore pressure is the pressure exerted by the formation fluids on the walls of the rock pores. The pore pressure supports part of the weight of the overburden stress, while the rock grains take the other part [Rabia, 1985]. Formations are classified based on the magnitude of their pore pressure gradients. In general, two …
The only way to obtain information, before well drilling, on the nature and characteristics of the subsurface, including the pore pressure prediction, is through geophysical prospecting. The seismic reflection method is the most important and extensively used geophysical method for oil prospecting. Although geophysicists and geologists use seismograms mainly for subsurface structural and lithological interpretation, …
Background gas enters the mud circulating system as the formation is drilled by the drilling bit and usually maintains a steady but low level. Additionally, as shales are circulated up the hole, the reduction in pressure explodes the shale particles releasing gas into the drilling mud. These are the most common sources of gas. Pressure …
D is an exponent which, relating drilling penetration rate to weight on bit per unit hole diameter, measures the formation’s ” drillability “. There were several attempts to link the drilling parameters to generate a measure of drillability. The best known was by Jorden and Shirley *, who demonstrated empirically that in homogeneous shale formations, …
By definition, abnormal pore pressure is any geo-pressure different from the established trend for the given area and depth. This article will introduce the six significant causes of abnormal pressure while drilling. Also, in the following articles, we will discuss its prediction and more. Pressure may be Subnormal pressures present few direct well-control problems. However, …