What's new in artificial lift: Part 1—twenty new systems are described for sucker rod and progressing-cavity pumping, plunger lift and gas lift

World Oil, April, 2006 by James F. Lea, Herald W. Winkler, Robert E. Snyder

Testing results have shown many advantages, i.e., fewer and longer strokes per minute, producing more oil and eliminating clocks by producing 24 hr/day. This is performed by the computerized system keeping an optimum fluid level in the annulus. This control is possible using lifting pressure instead of tension to measure in realtime and to instruct the computer as to the strokes per minute.

An economic value is recognized when maintenance is required. A special cable unit is brought out to reel up and repair the downhole pumping assembly and return it to bottom; no workover unit is needed. This pumping method is in an advanced testing phase and will be available in the near future.

PROGRESSING CAVITY PUMPING

Five PCP advances from two companies include: a three-component gas well deliquifying pump; a hydraulic power skid with power source, hydraulic motor and controller; a liquid level monitor that alters PCP speed; a new loop to simulate downhole pumping system conditions; and a new-version PCP software program.

PCP drive system dewaters gas wells. Hydraulic Energy Products, Inc., (Applied Energy Products, AEP, spinoff), Denver, Colorado, has developed a three-component drive system to automatically de-water gas wells, especially coalbed methane wells. The complete system is self-monitoring and regulating, with signal capability to alert the operator if drive speed goes above or below pre-determined set points. Variable speed with manual control is achieved by applying the Top Head Drive and the Hydraulic Power Skid only.

The direct Top Head Drive hydraulic, motor-driven unit from HEP is offered in four torque ranges and utilizes the conventional friction lock block to connect to the 1 1/4-in.-diameter polished rod, Fig. 8. The largest drive motor is capable of supporting string and water column weights to 5,000-ft depth, while delivering 2,000 bwpd; or 4,000 bwpd from 2,500 ft. The maintenance-free drive operates through a rotary union, replacing the conventional stuffing box.

[FIGURE 8 OMITTED]

Complete control of "back-spin" is achieved in conjunction with the HEP hydraulic power skid, and in the two larger sizes, a fail-safe brake provides release or dissipation of stored energy. The drive can be mounted on a threaded adaptor, to the flow tee, or secured on the standard API 8-bolt flange. The drive is presently offered in two sizes: 12 [in..sup.3] and 26 [in..sup.3]/ rev. At present, there are 10 drive heads running, with initial units exceeding two years without service or maintenance.

The HEP Hydraulic Power Skid, Fig. 9, is offered with natural gas-powered 2.5- or 4.0-1 engines or 460V electric motors up to 100 HP. The HEP design incorporates complete secondary containment of all liquids and a full enclosure to prevent water buildup. The variable volume hydraulic pump is electro-proportionally controlled, with a feedback loop to assure accuracy and volumetric/operating pressure efficiency. The onboard computer optimizes fuel mix and governs operating speed. It also monitors engine oil pressure, radiator temperature, hydraulic reservoir liquid level and temperature. The skid can reverse rotation of the Top Head Drive, with limited torque and speed, to dissipate stored energy, flush the PCP, or rapidly equalize fluid levels. The constant-speed electric motor drive system provides variable Top Head Drive speeds hydraulically and eliminates the need for a Variable Frequency Drive (VFD).