Continuous extruded solids discharge

A method for processing oil or gas well waste solids, the method comprising:

• receiving treated solids into a solids inlet, the solids inlet located in a front end of a casing of a pressurizing discharge unit, wherein the treated solids are exposed to a reduced pressure in an internal chamber of the casing of less than atmospheric pressure;
• adding water to the treated solids in the internal chamber through a water inlet located in the casing;
• rotating an extruder screw unit located in the internal chamber, the extruder screw unit having progressive screw sections corresponding to a conveying screw section, a mixing screw section and a pressurizing screw section, including:
• conveying, by the conveying screw section, the treated solids along a long axis length of the extruder screw unit, from the solids inlet towards a discharge end of the casing while the reduced pressure is maintained,
• mixing, by the mixing screw section, the treated solids and the water together, to form a paste, and
• conveying, by the pressurizing screw section, the paste towards the discharge end, and generating, in a portion of the casing downstream from the mixing screw section, a backpressure that is greater than atmospheric pressure;
• and
• extruding the paste through an orifice of a die assembly located at the discharge end while maintaining the greater than atmospheric backpressure on the paste in the internal chamber.

An oil or gas well drilling system, the system comprising:

• a feed line configured to transport waste solids to a thermal extraction unit, the thermal extraction unit configured to extract hydrocarbon and water vapor from the waste solids to form treated solids, wherein the treated solids are maintained at a reduced pressure of less than atmospheric pressure;
• a flow conduit connected to transport the treated solids to a pressurizing discharge unit while maintaining the reduced pressure, wherein:
• the pressurizing discharge unit has a casing, the casing including:
• a solids inlet configured to receive treated solids into a front end of the casing, wherein the treated solids are exposed to a reduced pressure in an internal chamber of the casing of less than atmospheric pressure;
• a water inlet configured to receive water and add the water to the treated solids in the internal chamber;
• an extruder screw unit, the extruder screw unit having progressive screw sections located inside the internal chamber and corresponding to:
• a conveying screw section configured to convey the treated solids along a long axis length of the extruder screw unit from the solids inlet towards a discharge end of the casing while the reduced pressure is maintained,
• a mixing screw section configured to mix the treated solids and the water together to form a paste, and
• a pressurizing screw section configured to convey the paste towards the discharge end and to generate, in a portion of the casing downstream from the mixing screw section, a backpressure that is greater than atmospheric pressure;
• and
• a die assembly configured to extrude the paste through an orifice of the die assembly located at the discharge end while maintaining the backpressure on the paste in the internal chamber.