Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well, which are connected together for regenerative assist. Synchronized variable stroke and variable speed pump down control is provided, such that should pump down be encountered in one of the wells, programmable controllers (46) reduce the speed and the stroke of a ram unit (26) for a pumped-down well by the same percentage, to maintain a constant cycle time between upstrokes and down strokes such that the ram unit (26) of the pumped down well will remain synchronized with a ram unit (26) of the other well. Preferably the speed and the stroke of the ram unit (26) of the pumped down well will be decreased by 1.5% per stroke when pump down is detected, and will be increased by 3% per stroke until a constant fluid level is reached.

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well, which are connected together for regenerative assist. Synchronized variable stroke and variable speed pump down control is provided, such that should pump down be encountered in one of the wells, programmable controllers (46) reduce the speed and the stroke of a ram unit (26) for a pumped-down well by the same percentage, to maintain a constant cycle time between upstrokes and down strokes such that the ram unit (26) of the pumped down well will remain synchronized with a ram unit (26) of the other well. Preferably the speed and the stroke of the ram unit (26) of the pumped down well will be decreased by 1.5% per stroke when pump down is detected, and will be increased by 3% per stroke until a constant fluid level is reached.

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well (preferably with each ram unit (26) having three hydraulic rams). Each hydraulic ram units is connected to first ram pump (18) and a second ram pump (20). The drive shaft (40) of the first ram pump (18) is coupled to the drive shaft (38) of the second ram pump (20) and to a rotor of a drive motor (16). The ram pump (18) and the ram pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the ram pump (20) and during the up stroke of the hydraulic ram (26) the ram pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).

Abstract: A universally stable oil-well-ship turret (1) has a circumturret cylinder (2) with an inside periphery sufficiently greater than an outside periphery of a turret cylinder (7) to allow vertical positioning of the turret cylinder within the circumturret cylinder in opposition to variations from verticality of the circumturret cylinder in response to effects of wave and weather conditions on a marine vessel in which the circumturret cylinder is positioned rigidly. A plurality of horizontal and vertical bearings (10, 11) are pressure-cylinder actuated to maintain horizontal attitude of a turret flange (8) from which the turret cylinder is extended downward vertically into the circumturret cylinder. Sensor-responsive automation that is self-checking for reliability, selective manual operation and computer controls (52, 54) are provided. Appropriate redundancy and backup are provided for all systems, components and features. A use method is described.

Abstract: A controlled-pressure multi-cylinder riser tensioner has a plurality of preferably six control-cylinder units (1) with proximal ends (2) attached pivotally to a bottom surface of an operational floor (3) and distal ends (5) attached pivotally to a riser-tensioner ring (6). Pressure lines (20, 38) in communication with opposite ends of the control cylinders lead to sources of pressure (46, 47, 48, 52, 53, 62, 63) that are separately controlled. Stroke length of the control-cylinder units is typically 50 feet. Projection of the control-cylinder units downwardly into a moon pool (9) avoids their obstruction of work space on an operational floor (3) of a vessel (4). Positioning pneumatic and hydraulic machinery (10) below deck with tubing leading to the control cylinders lowers center of gravity for marine stability. An over-capacity for tensioning the marine riser with a portion of the control cylinders inactive or incapacitated increases reliability.