Downhole separation of water and solids from an oil mixture

摘要

An apparatus for separating water and solids from an oil/water mixture is located downhole within the pipework of an oil-well and comprises hydrocyclone 6 and centrifugal device 10. Hydrocyclone 6 achieves separation of the solids from the oil/water mixture and said mixture is then separated using centrifugal device 10. Oil-continuous or water-continuous mixtures can be separated. The separated oil is then pumped to a platform above sea-level/on the surface. Means for causing coalescence such as electrostatic coalescence unit 8 may be included prior to the centrifugal device 10 in order to promote water droplet formation and thus more efficient oil/water separation. A minimum water droplet size of 10-15 Ám is required for effective separation. The speed of centrifuge 10 can be varied depending on the amount of water (10% to 90%) to be separated from the oil/water mixture. A re-injection pump 12 may also be included to return the separated water to the oil source. The separated solids may be returned with the water or they may be transported to the surface with the separated oil.