Exploration strategies have caused large investments in the search for offshore production. Many of these areas are characterized by poorly consolidated sediments and associated problems of gumbo shales. These problems not only slow down problems of gumbo shales. These problems not only slow down drilling procedures, but in some cases may cause the loss of the hole. These offshore areas have high hydrocarbon potential and high drilling costs. Control of gumbo shales during drilling has become the number one problem in these areas.
Many papers have been written on gumbo shale drilling but usually the control method is based upon a particular remedy not necessarily applicable to all cases. This paper explores the nature of gumbo shales and presents a survey of the many remedies that have been recommended. Solutions to the effective drilling of gumbo shales are suggested based upon the nature of the shale.
Drilling fluid design is the cure for problems caused by gumbo shale. Five remedies for controlling gumbo problems have been used:
coating the shale surface,
inhibiting the shale,
removing water from the shale osmotically,
controlling shale influx by increasing the hydrostatic head, and
removing shale cuttings from mud.
The drilling fluid components used for each of the five control measures are evaluated in terms of effectiveness in the different types of gumbo shale. Prescriptions for drilling fluid control are suggested utilizing the five methods of control. Drilling rates and solids removal equipment are also discussed as they contribute to the gumbo shale control problem.
There are some very effective remedies for gumbo shale problems but the proper treatment must be used for a specific kind problems but the proper treatment must be used for a specific kind or type of gumbo shale problem. A new Sun invention will be disclosed as a gumbo control device.
Gumbo shales are composed of a range of materials which either have a very high content of silt-sized and/or clay-sized materials or a very high content of minerals of the montmorillonite type. Both become exceedingly sticky and tenacious when water contents are high. The great plasticity which results causes the gumbo to stick to surfaces and when mechanically mixed or sheared builds up large plastic masses.