Published January 2012
Problems of exposing of oil-and-gas bearing formations and geological justification of wells design selection in the field named after March 8
T.S.AbdullazadehThe article deals with the problems of exposing of PT V, VII and VIII horizons in the gas-condensate field named after March 8 without failures and complications. Despite the fact that a lot of wells have been designed to these horizons up to now, difficult geological conditions did not allow for them to be brought to the target depths. It seems that the main reason for that is the presence of facilities incompatible in drillability conditions in the section during the joint exposing of V, VII and VIII horizons. This fact was not taken into account and the relevant facilities were not isolated from each other. It should be stated that in the field March 8 in PT section the silt-sand formations in the upper part of V horizon behave as V, VII and VIII horizons do, that is these formations do not have high abnormal formation pressure like in the other fields of Baku archipelago. From the practical point of view it is known that the lowering of the second intermediate string higher than 150-200 m from V horizon roof allowed for PT V, VII and VIII horizons to be jointly exposed with relatively low density of drilling mud. However, later while drilling these horizons, serious complications took place in many other wells, and it gives ground to suppose that joint exposing of these horizons becomes impossible. The situation is concerned with the decrease of formation pressure of VII horizon. As a result of intensive development of this horizon, the initial formation pressure of silt-sand formations of V horizon and overlying ones remained, and consequently the mismatch of geological conditions of V, VII and VIII horizons development arose. In order to solve the problem all the complications that arose after drilling were analyzed and the results of geophysical investigations were studied, as a result of which five intervals incompatible on drillability conditions, including three zones with abnormal high formation pressure, were determined in the field section. Considering geological-lithologic characteristic and pore pressures distribution in the field section, a rational design for newly drilled wells is suggested.
