SUBSURFACE SUCKER ROD PUMPS (SSRP)
The manufactured SSRP correspond to the API Spec. 11 AX.
The main component of SSRP is a barrel which is manufactured out of a precision pipe. The working area of the barrel is nitrided to the depth of 0.008…0.020 inches, the hardness of the nitrided coating is 870–1124 HV, or it can be chrome plated with the coating depth of 0,003 inches and the hardness of 700…900 HV.
BASIC CHARACTERISTICS OF PRECISION BARRELS
|Conventional nominal ID, inch||1.06, 1.25, 1.50, 1.75, 2.25, 2.75, 3.75|
|Tolerance for ID, inch||0.002|
|Tolerance for barrel bore axis linearity per 3.3 ft base length, inch, no more||0.003|
|Maximum difference of internal diameter dimensions, inch||0.001|
|Roughness of inside surface, RA||32|
All-metal plungers for SSRP, having the length from 4 to 15 ft, match the barrel in one of the five fit groups according to the API Spec. 11 AX. The plunger linearity tolerance is 0.002 inches on the length of 4 ft. The following three methods of hardening the outside plunger surface are offered: chrome plating, flame spraying with subsequent fusing and nitriding.
The valves for SSRP are set in «ball-and-seat» couples made of stainless bearing steel (A1) *, cobalt alloy (B1, B2) *, tungsten carbide (C1) * and titanium carbide (C3) *; the two elements are grinded in pairs to provide leak-proofness.
*The symbols as per API Spec. 11 AX.
Specialty SSRP are designed for complicated well conditions (high viscosity, high GOR, sand presence) and boost the in-use reliability of SSRP.
SPECIFICATIONS OF SUBSURFACE SUCKER ROD PUMPS
|Pump type||Designation, API||Plunger stroke, ft||Head, ft||Tubing diameter, inch||
Connecting thread to rods
|Insert pump with top lock||20-106 RHAM||4… 11.5 up to 13||up to 8200||2 3/8||3/4”||N14-20|
|20-125 RHAM||up to 7200|
|25-150 RHAM||2 7/8||N14-25|
|30-225 RHAM||3 1/2||7/8”||N14-30|
|Insert pump with bottom lock||20-106 RHBM||up to 11500||2 3/8||3/4”||N14-20|
|25-150 RHBM||2 7/8||N14-25|
|25-175 RHBM||up to 10000|
|30-225 RHBM||up to 8200||3 1/2||7/8”||N14-30|
|Tubing pump with
|20-125 THM||4… 11.5 up to 13||up to 5000||2 3/8”-8EU
|30-275 THM||Up to 3900||3 1/2”-8EU||7/8”|
|40-375 THM||up to 3300||4 1/8”-8EU||1”|
|Tubing pump with a breakable pin*||20-125 TH||up to 5000||2 3/8”-8EU
|30-275 TH||Up to 3900 3||3 1/2”-8EU||7/8”|
|40-375 TH||up to 3300||4 1/8”-8EU||1”|
|TUBING PUMPS||FIXATION OF ROD PUMPS IN TUBINGS|
SPECIALTY SUBSURFACE SUCKER ROD PUMPS
|TUBING PUMP WITH A BREAKABLE PIN||TWO-PLUNGER SSRP FOR PRODUCING HIGHLY VISCOUS OIL|
|Tubing pump with a breakable pin is meant for crude production. When lifting the pump out of the well, the formation fluid draining from the tubing and the pump takes place in the hole of the breakable pin.
After lifting the plunger out of the well, a steel bar (OD – 1.5 inches; 4–5 ft length) is thrown down into the well to open the area of the breakable pin.
Thus, the breakable pin allows lifting the subsurface equipment without the formation fluid.
|The two-plunger insert pump with two-stage compression and an upper lock is designed for producing crude of high viscosity (up to 0.3 Pa•s), containing up to 0.062 lb / ft3 of mechanical impurities.
On plungers downstroke, a rarefaction is created in the area of the barrels which is situated between the two plungers. It happens so that the lower valve of the valve unit opens and the formation fluid enters this area. The closed upper valve perceives the pressure of the fluid column and creates an extra downward directed load useful to overcome hydraulic resistance in the pump and friction forces in the sucker rod string. The latter is very important, as the main obstacle for pumping out high-viscosity fluid is balking of the sucker rods because of excessive friction forces.
The superload is:
Р = p dp / 4 (H – h) g,
where dp – diameter of plunger-divider;
H – pump setting depth;
h – depth of pump setting under dynamic head;
g – specific weight of produced fluid.
On the following upstroke of the plungers the fluid is displaced from the interplunger area through the open upper valve of the valve unit into the tubing string.
|TWO-PLUNGER SSRP FOR PRODUCING OIL WITH EXCESSIVE MECHANICAL IMPURITIES CONTENT AND HIGH GOR||
|TUBING PUMP WITH A TOP DRAINER, AN AUTOMATIC COUPLER AND A SLUDGE TRAP|
The two-plunger insert pump with two-stage compression and with a bottom lock is designed for fluid production, containing up to 0.062 lb / ft3 of mechanical impurities and up to 25 % of free gas at the pump inlet.
On plungers upstroke a rarefaction is created in the area of the lower barrel, located over the standing valve. This allows the formation fluid entering this area with the standing valve opened. On the following downstroke the fluid being compressed flows from this area into the area, located between the plungers, the lower valve opened. Since the interplunger area is smaller by volume than the lower barrel area, the pressure of the gas-liquid mixture in it will be greater than a suction one. On the next upstroke the fluid between the plungers, being again compressed, is displaced into the tubing string with the upper valve opened.
The repeated compression of the fluid in the pump allows avoiding pump blocking when the gas content is high.
The drainer device provides fluid drain from the tubings directly when withdrawing (pulling out) the plunger before lifting the pump, without using a catcher or a breakable pin.
The automatic coupler allows lowering the pump with the drainer device cone preliminary mounted in the seat, thus providing reliable sealing of the drain unit.
The cavity between the sludge trap body and the external barrel surface serves as a collector for mechanical impurities, settling down when lowering sucker rods into a well and on pump shutdown. The protection bushing, fitted in the sludge trap cone prevents from the ingressing of contaminants into the pump barrel cavity. The pump design permits to minimize the amount of «adverse space» (the cavity between the standing and traveling valves with the lower plunger position), and also to equalize pressure inside and outside of the barrel and to allow relieving its tensile stress.
|SSRP, EXCLUDING THE PLUNGER PAIR BALKING||
|SSRP WITH A RELIEF VALVE FOR PRODUCING OIL WITH A HIGH GOR|
This design of the pump employs a short barrel and an oversized standing valve with a breakable pin. The pump is used when the mechanical impurities content is more than 0.062 lb/ft3.
Increased lifetime because of the constant contact of the barrel and the plunger makes it so that the mechanical impurities practically do not enter into the plunger-pair clearance. Nowadays the pumps are used in Tatar Republic, Bashkiria, Kazakhstan and Sakhalin. The working time of PKNM equipment is increased in 1.5–2 times if to compare it with the standard SSRP.
The SSRP construction is patented.
The pump design includes a relief valve that excludes standing valve’s blocking by gas that is released in the cavity under the traveling valve.
SSRP FOR PRODUCING HIGH VISCOSITY OIL
The pump is meant for producing high viscosity
The pump of a special design includes a fixed barrel inside of which a barrel with a traveling
ADDITIONAL DEVICES FOR SSRP
SECTIONAL NIPPLE PLUNGER
|Conventional pump size||L, ft||l, ft||Designation, API||D, inch||d, inch||Tubing thread|
|LOCK SUPPORT «CONE IN CONE»||LOCK SUPPORT (ОМ TYPE)|
VALVE WITH A BREAKABLE PIN
It is used for draining the fluid off the tubing string, when pulling up. The fluid drain takes place when a bar is dropped in the tubing string, cutting away the breakable pin and opening the drain hole. The advantage of this design is absolute reliability as opposed to the commonly used valve with a bayonet-type catcher, and this makes it possible to exclude cases of pulling out the tubings, filled up with formation fluid. For production of viscous oil there is used the standing valve with a larger flow area, also equipped with a breakable pin.
|The fine filter is mounted at the pump inlet and provides the purifying of the formation fluid from contamination when it enters the pump simultaneously through the tubing and from the
annular space. Fluid filtration takes place when it goes through the screen, fixed in the body, and
through the holes in the sleeve, built in the top sub of the filter. The fine filter is designed to avoid the ingress of mechanical impurities at the inlet of the Subsurface Sucker Rod Pumps.
ADJUSTABLE DOWNHOLE FILTER
|PROTECTIVE DEVICES FOR SSRP|
The filter is intended for protection of the sucker rod pump against ingress of contaminations contained in the pumped-out fluid. The filter consists of a body with orientating ribs and longitudinal slots, inside of the body there is a spring acting as a filter-element. Fineness of filtration (from 0.0078 to 0.0314 in) is provided by adjustment of between-coil clearance of the spring with the help of the adjusting screw with a rod.
|THE OPERATION SCHEME OF THE SSRP PROTECTIVE DEVICES|
AN AUTOMATIC COUPLER AND A SLUDGE TRAP
The automatic coupler is designed to connect the sucker rod string with the SSRP plunger directly in the
well. This allows lowering of the tubing pump barrel and plunger together and to avoid fouling of the barrel
with mechanical impurities (scale, mud etc.), that occurs when the barrel and the plunger are separately
run into the well. The sludge trap protects the pump from the side of the tubing space. The contaminants
(scale, mud etc.), settling down when lowering the rod string, are accumulated in the trap cavity and do not get into the pump.
The Gas-Sand Anchor is installed at the pump inlet of SSRP and serves for protection against free gas and mechanical impurities.
Gas-sand anchor dimensions, inch:
Longitude (without mechanical impurities collector) – 93.31 inches; OD – 4.134 inches; Weight – 125.9 pounds; Tubing diameters – 2 3/8; 2 7/8; 3 inches. The number of tubings installed as mechanical impurities collector – 2-3 pcs. Production rate – 314.5 bls/day.
Anchor setting depth under the dynamic head – up to 197 ft.
Watercut, % - up to 99;
H2S content, lb/oz – not more than 0.0037;
Hydrogen ion consentration – рН 4…8;
Mechanical impurities content, lb/oz – more than 0.0969;
Viscosity, mPa•s – 200;
Free gas content at the pump inlet, % - up to 50.
Gas-sand anchor is connected with the lower coupling of the lock support with the help of the tubing, connected with the upper sub. Or it can be installed on the standing valve body in the tubing pump, using the upper sub as a help. Gas-sand anchor operates on principles of centrifugal, gravitational and mechanical cleaning.
The anchor consists of a body, the upper part of which has perforations (b), through the perforations the pumped fluid goes to the inner part(c) of the anchor.
Getting to the cavity (c), the fluid goes down between the body walls and intake tube having slow velocity, which lets the gas, that the fluid contains, go up and then go out through the perforations (b) into the intake tube space.
The intake tube (3) is extended at the bottom (4), it helps to increase the flow velocity with mechanical impurities content. When getting into the intake tube opened at the bottom (3), the fluid flow changes direction on 180о, thus separating the mechanical impurities and the fluid. Through the inner cavity (d) of the intake tube (3), the fluid goes to the pump. The separated mechanical impurities are collected in the collector which consists of tubings and is installed on the bottom sub (5). The bottom tube has an end cap (6).