Isolation container for a downhole electric pump

#1. Field of the Invention

#This invention relates to an isolation container for use with a downhole electric pump and the method of its application. The downhole electric pump is of the type used in the oil and gas industry. Such pumps usually are used for pumping oil and gas production to the surface when naturally occurring formation pressure is insufficient to raise the oil and gas to the surface. However, downhole electric pumps are also used in a downhole environment to increase the pressure of pressurized and un-pressurized fluids supplied from the surface. In these instances, the pressurized fluid is injected into the adjacent oil and gas bearing formation to treat or “fracture” the formation. In other applications, a downhole electric pump pressurizes fluid for injection into a formation to urge oil in the area of the wellbore in the direction of another nearby well where the oil is more easily produced. In these operations, any number of wells may be used to “chase” the underground oil to the collecting well. FIG. 1 is a sectional view of a prior art configuration utilizing a downhole electric pump assembly to inject high pressure fluid into a formation. The prior art configuration of FIG. 1 has a surface platform 10 (shown schematically) extending above ocean surface 12. Production riser 14 extends downwardly to hydraulically actuated connector 16 which is sealingly connected to wellhead housing 18 in a manner well known to those of ordinary skill in the art. Casing 20 extends from wellhead housing 18 to subsurface formation 22 and is cemented in place in ocean floor 24. Production tubing 26 extends from surface platform 10 through wellhead housing 18 to downhole packer 28 positioned in casing 20. Extension nipple 30 and coupling 32 connect production tubing 26 to downhole electric pump assembly 34. Lower extension nipple 36 extends from downhole electric pump assembly 34 through lower downhole packer 38 to that area of the wellbore adjacent subsurface formation 22. Downhole electric pump assembly 34 includes electric motor 40, motor seal section 41 and downhole electric pump 42. Electrical cable 44 extends from the surface to electric motor 40 in a manner well known to those of ordinary skill in the art.

#A typical sequence of operation has fluid 46 supplied from surface platform 10 through production tubing 26 to downhole electric pump assembly 34 where it is taken into the pump assembly through intake ports 35. Thereafter, downhole electric pump assembly 34 increases the pressure of fluid 46 and then discharges it through lower extension nipple 36 into subsurface formation 22. In this manner, pressurized fluid 46 may be used to cause fracturing of the subsurface formation 22 to increase production capacity or it can be used to urge oil to another area of a field for collection at another well.

#So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.

#It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

#These and other objects and advantages of the present invention are set forth below and further made clear by reference to the drawings, wherein:

#Referring to FIG. 2, a sectional view of an isolation container of the present invention utilizing a downhole electric pump assembly to inject high pressure fluid into a formation is shown. Those items which are the same as in the prior art configuration of FIG. 1, retain the same numerical designations. The configuration of the present invention has a surface platform 10 (shown schematically) extending above ocean surface 12. Production riser 14 extends downwardly to hydraulically actuated connector 16 which is sealingly connected to wellhead housing 18 in a manner well known to those of ordinary skill in the art. Casing 20 extends from wellhead housing 18 to subsurface formation 22 and is cemented in place in ocean floor 24. Production tubing 26 extends from surface platform 10 through wellhead housing 18 to isolation container 100 positioned in casing 20. Blind coupling 102 is threaded and sealed to production tubing 26. Blind coupling 102 connects downhole electric pump assembly 104 within isolation container 100. Lower extension nipple 36 extends from downhole electric pump assembly 104 through isolation container 100 and lower downhole packer 38 to subsurface formation 22.

#Downhole electric pump assembly 104 includes electric motor 106, motor seal section 107 and downhole electric pump 108. Electrical cable 44 extends from the surface to downhole electric pump assembly 104 in a manner well known to those of ordinary skill in the art. Isolation container 100 is designed to isolate the wellbore casing 20 from fluid supplied from the surface including any pressure under which the fluid is delivered to the downhole region of the wellbore. Isolation container 100 may include check valve 110 for releasing any air trapped in pressurized fluid 46. Additionally, seal rings 112 and 114 provide sealing around tubing 26 and lower extension nipple 36. Isolation container will be typically be constructed of corrosion resistant material to withstand corrosive effects of pumped fluid and will also have sufficient wall thickness to resist any pressure of the fluid as it is delivered from the surface.

#A typical sequence of operation has fluid 46 supplied from surface platform 10 through production tubing 26 and into isolation container 100. Blind coupling 102 has a plurality of radially disposed ports 116 therein. Ports 116 provide fluid communication for fluid 46, thereby allowing fluid to flow into annulus 118 between downhole electric pump assembly 104 and isolation container 100. Fluid 46 then flows into inlet ports 120 of downhole electric pump 108 where its pressure is increased or boosted. Pressurized fluid 46 is then discharged through lower extension nipple 36 through packer 38 and into subsurface formation 22. Pressurized fluid 46 may be used to cause fracturing of the subsurface formation 22 and thereby increase production capacity or it can be used to direct oil to another area for collection at another well. In this manner, the isolation container 100 allows fluid 46 to be boosted in pressure downhole without exposing the adjacent formation to pressurized fluid 46.