Slippage Past Plungers

In slippage past a closely fitted plunger, the flow between the  plunger and the barrel is in the viscous range, so leakage or slippage is inversely proportional to the absolute viscosity and to the plunger length. Technical Data used in the field explained in petroleum courses in Rawalpindi. It is directly proportional to the plunger diameter, the differential pressure between the two ends of the plunger, and the cube of the diametric clearance.

The absolute viscosity of well fluids commonly pumped will range from approximately 1 to 100 cp at temperatures existing at the pump setting. In some cases the viscosity may be as high as 1,000 cp. As a result of viscosity variations, the slippage past the plunger of a particular plunger-pump assembly with a given plunger fit, length, and diameter may vary by as much as 100 to 1 under fairly common conditions. and as much as 1,000 to 1 under extreme conditions with the same differential pressure across the plunger. Some more details of petroleum courses in rawalpindi are as under.

Thus it is seen that a plunger pump may operate with acceptable efficiency in a well producing a highly viscous oil, whereas the same pump operated at the same speed and stroke may fail to deliver any oil to the surface when installed at the same depth in a well producing oil of low viscosity.

If we assume that the volume of the barrel below the plunger is completely filled during the upstroke, this rate of leakage can occur only during the upstroke, or approximately one-half of the total time. The net slippage past the plunger is 5.72 cu in./min, or 0.85 B/D. The displacement of a 21/4-in. pump operating at fifteen 48-in. strokes per minute is 426 BID, and the slippage in this case is only about 0.2%, which is insignificant. The results of this and other plunger clearances with 3-cp oil. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join oil field after petroleum courses in islamabad.

Pump Selection

The selection of a proper subsurface pump for the application is sometimes a point of conjecture. Technical Data used in the field explained in petroleum courses in Rawalpindi, The following recommendations generally are accepted as suitable for most applications.

API pump classifications. There are many variations of the pumps shown, some within the specifications of API and some that are non-API that will still perform the desired function of pumping oil to the surface.

A stationary-barrel rod pump with top seating hold down. This is a pump that is run into the well with the sucker rods. In this pump the plunger is attached to, and moves up and down with, the sucker-rod string. Some more details of petroleum courses in Rawalpindi are as under.

The barrel is held stationary at its top end by the seating assembly. The barrel is on the left and the plunger assembly is on the right. This is the preferred seating for the rod pump when possible. The top seating hold down provides a seal just below the cage, where the well fluid is discharged into the tubing, so sand or other solid particles are prevented from settling between the barrel and the tubing, and the pump is not apt to become stuck in the tubing by packed sand.

Tubing pumps have larger bores and correspondingly greater displacements for a given stroke length than rod pumps that can be used with the same size tubing. Therefore, tubing pumps commonly are used where it is necessary to lift large volumes of fluid and a pump of high displacement is required. A tubing pump has fewer working parts and is often lower in cost than a rod pump of corresponding size. However, the greater volume and resulting heavier fluid load may cause a loss in this advantage  by excessive sucker rod and tubing stretch. Also, the entire tubing string must be pulled to service the barrel of a tubing pump. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join oil field after petroleum courses in Islamabad.

Subsurface Sucker-Rod Pumps

The general principles of sucker-rod pumps as used in oil wells are well known. Technical Data used in the field explained in petroleum courses in Rawalpindi. Fundamentally, they consist of the usual simple combination of a cylinder and piston or plunger with a suitable intake valve and discharge valve for displacing the well fluid into the tubing and to the surface. However, the variety of problems encountered in pumping oil wells has resulted in a great number of modifications of this fundamentally simple unit to make it more effective for the various conditions encountered.

In general, the pumping of oil wells often presents the widest variety of advise conditions possible in a single installation of any pumping application. These may include high discharge pressures; low intake pressures; severe abrasive conditions resulting from sand or other solids in suspension: severe corrosive conditions resulting from corrosive gases or salt waters; deposits of lime, salts, or other solids from the water pumped; paraffin deposits from the oil pumped; and the requirement that the pump handle liquids, permanent gases, and condensable vapors under the pressure and temperature conditions existing at the pump. Strong magnetic forces that may interfere with valve action when the valves are made of magnetic material are encountered often. And electrolytic corrosion is likely to occur as a result of using dissimilar materials. Some more details of petroleum courses in rawalpindi are as under.

The bores of reciprocating oil well pumps can range from 1 to 4% in. in diameter. The 4X-in. bore pump has a displacement about 22% times that of the l-in. pump for a given speed and stroke length. This wide range of pump capacities is necessary to permit selection of the most efficient and economical pumping equipment for all conditions encountered. In many wells it is necessary to pump large volumes of water along with the oil, so the pump must have a capacity several times that indicated by the net oil production. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join oil field after petroleum courses in Islamabad.

ESP System Typical Installation

A typical ESP installation is The ESP system’s major surface and downhome equipment is shown. Technical Data used in the field explained in petroleum courses in Rawalpindi, In this installation, the available surface power is transformed to the down hole power requirements by three single-phase transformers.

 The transformed power is supplied by a power cable to a switchboard and then through a junction box and wellhead/tubing support. The power cable is run in with the production tubing string and is banded to the tubing to prevent mechanical damage during installation and removal. The power cable is spliced to a motor flat cable, which is banded to the exterior of the pump-protector motor unit. The centrifugal pump is located at the top of the down hole unit. Some more details of petroleum courses in rawalpindi are as under.

The pump is hung on the tubing string by the discharge head. Below the pump is a standard intake, which provides for fluid entry to the pump. The center component is the protector. The protector both equalizes external and internal pressure and isolates the motor from the well fluid. The lowest component is the motor, which drives the centrifugal pump. Note that the down hole unit is landed above the perforations. This is necessary so that fluid entering the well flows past the motor. This flow cools the motor, which is otherwise likely to overheat and fail. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join petroleum courses in islamabad.

Electric Submersible Pumps

The electric submersible pump (ESP), sometimes called “submergible, ” is perhaps the most versatile of the major  oil-production artificial lift methods. Technical Data used in the field explained in petroleum courses in Rawalpindi.  This chapter provides the reader with a broad understanding of the key factors in selection, installation, and operation of electric submersible pumps. ESP topics covered include the ESP system; applications; ESP system components, selection data and methods; handling, installation, and operation; and troubleshooting.

The ESP system comprises a downhome pump, electric power cable, and surface controls. In a typical application, the downhome pump is suspended on a tubing string hung on the wellhead and is submerged in the well fluid. Some more details of petroleum courses in rawalpindi are as under.

The pump is close-coupled to a submersible electric motor that receives power through the power cable and surface controls.

The ESP has the broadest producing range of any artificial lift method. The standard 60-Hz producing range of the ESP extends from a low of 100 B/D of total fluid up to 90,000 B/D. Variable-speed drives can extend the producing range beyond these rates. Although most operators tend to associate ESP’s with “high volume” lift rates, the average ESP produces less than 1,000 B/D of total fluid in continuous operation.

ESP’s are used to produce a variety of fluids and the gas, chemicals, and contaminants commonly found in these fluids. Currently ESP’s are operated economically in virtually every known oil field environment. The WOR is, in general, not significant in assessing an application. TSK Training for Skills and Knowledge is the best institute in Rawalpindi Islamabad for Pakistani Students who wants to join oil field after petroleum courses in Islamabad.