PRODUCTION

     There are a countless number of pumps; drive units and wellhead configurations that can be used in conventional oil production.  I am going to discuss the basic ones – the down-hole pump, drive unit and wellhead, that are used at the ExxonMobil Celtic field which is approximately 40 miles northeast of Lloydminster.

    Progressive Cavity Pumps or PCP’s have been developed and are the single biggest reason that heavy oil production has become more successful in recent years. These PCP’s are used extensively in the Celtic field.  The PCP allows more sand to be pumped out of the wells, which helps produce more oil.  The PCP pump uses a rubber stator that is mounted on the end of the production tubing (see Fig.1  ).  A rotor, which looks similar to a wine corkscrew, is attached to the end of a series of rods, which run from the stator all the way up to the wellhead, and is attached to some sort of a drive unit.  The drive unit spins the rods and thus makes the rotor turn inside the stator, which is attached solidly to the production tubing.

FIG. 1

            When the rotor is placed inside the stator a series of cavities are formed.  As the rotor turns these cavities progress from the suction end of the pump up to the discharge end (see Fig. 2 ).  The pump then transports the fluid up through the pump and up the tubing string to the surface wellhead and eventually into the production tank.  The volume of fluid produced can be changed by the speed of the rotation of the rotor.

                    FIG.2                                                                                 FIG.3

            The wellhead drives at the ExxonMobil Celtic field are hydraulically driven from a skid unit, which is run by an electrically powered motor.   The electric motor runs a hydraulic pump ( see Fig. 3 ), which provides the hydraulic pressure to run the hydraulic motor on the wellhead drive that turns the rod string and rotor down hole forcing the oil, sand and water to be forced up the production tubing.  When the oil production reached the wellhead it goes through a flow line which is attached to the production tank.

              The oil production that is pumped out of the reservoir is approximately 16 – 18 C and must be heated up in order for the oil, water and sand to separate out.  The production tank has a burner located about 2 meters high from the bottom of the tank.  The burner, which can burn either natural gas or propane, heats the oil production from 16 C to approximately 70 C.  By heating the oil production the oil will go onto the top of the water and the sand will drop to the bottom of the production tank.

              The oil is then loaded onto the trailer of a semi-tractor/trailer unit through the production tank spout (see Fig. 4 ).  The oil is then trucked to the battery treating facility where it undergoes further processing.  The water in the production tank is pumped onto a semi-tractor/trailer unit through a 75 mm valve located about 1 m from the bottom of the tank.  The water is then hauled to the battery facility and pumped off into a produced water tank where it is pumped from there and down a disposal well down into an absorbent formation.  The sand that has settled to the bottom of the production tank is removed by a vacuum truck, which sucks out the sand from a 100 mm valve located at the bottom of the tank.  The sand is then trucked to the ExxonMobil Celtic sand disposal where it is pumped down hole into an permeable formation.  A production operator checks each well daily keeping records of the gross amount of production made, oil levels of the hydraulic unit, temperature of the production tank and what levels the oil, water and sand are in the production tank so he can have the appropriate trucks haul out the correct fluids.

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