DEVICE FOR LOWERING CABLE IN WELL Russian patent published in 1999 - IPC

FIELD: oil and gas production industry. SUBSTANCE: device is used for carrying out operations connected with investigations of oil wells with mouth pressure. Device is made in the form of positive-displacement hydraulic drive which comprises source of hydraulic energy, distributing and shut-off - throttling unit, and output driven member (hydraulic motor). Source of hydraulic energy is made in the form of two differential hydraulic cylinders with unequal value of ratio of larger area in stage of stepped piston and smaller area of other stage of stepped piston. Located between two pistons of hydraulic motor is split pulling bush which is used for drawing cable through sealing gland of lubricator. Both pistons of hydraulic motor are provided with hollow rods which are directed in opposite sides. Rods are sealed together with pistons in hermetic cylindrical body with creation of working spaces in it. Pistons interact with pulling split bush which is installed in body with possibility of combined reciprocating motion. Working space of first differential hydraulic cylinder with smaller ratio of areas of stages in its stepped piston located at side of larger step of its piston is connected by passage (hydraulic line) with space of high pressure in well mouth. Similar working space of second differential hydraulic cylinder is connected by passage through distributing unit with same space of high pressure in well mouth with drain of hydraulic fluid into environmental medium. Working space located at side of smaller stage of stepped piston of first differential hydraulic cylinder is connected by passage with working space of hydraulic motor. This working space is located at side where device is connected to well mouth. Similar working space of second differential hydraulic cylinder is connected by passage with working space of hydraulic motor. This working space is located at side where device is connected to lubricator. Due to delivery of higher hydraulic fluid (oil) pressure than pressure of working medium (water) in well mouth into working under-piston spaces of hydraulic motor, ensured is any required axial compression of drawing split rubber bush located between these pistons in enclosed volume that is reliable engagement of this soft rubber bush with cable. Due to delivery of different pressure of hydraulic oil coming from two different differential hydraulic cylinders ensured is step-by-step movement of cable together with drawing split rubber bush clamped between pistons downwards into well. Cable is subsequently returned from well upwards when soft rubber bush is released. Application of aforesaid embodiment of device improves reliability of operations due to less wear of cable. Reduced is labour-intensity in performing geophysical investigations due to power-operated drive with utilization of practically free energy of working medium (water) taken from well mouth. EFFECT: higher efficiency. 1 cl, 4 dwg