Live well injection

Abstract

An apparatus and method for injecting and/or withdrawing items into/from a pressurized downhole, pipeline or the like when carried on or by a tubular length are disclosed. The apparatus can include two or more pressure sealing units for sealing against the length as it is injected. The sealing units can be joined by a pressure lock section, and the sealing units can be movable between a sealed position in which they are sealing against the tubular length and a retracted position. The apparatus may also include means for controlling pressure in the pressure lock section, in which the sealing units can be selectively and sequentially moved from the sealed position to the retracted position to allow introduction of an item therethrough, and in which the pressure lock section is selectively pressurizable and depressurizable to allow the item to move from low to high or high to low pressure during injection or removal.

We claim: 
     
         1 . An apparatus for injecting or withdrawing items into or from a pressurized downhole, pipeline when carried on or by a tubular length comprising:
 two or more pressure sealing units for sealing against the length as the item is injected, the sealing units being joined by a pressure lock section, the sealing units being movable between a sealed position in which they are sealing against the tubular length and a retracted position; and   means for controlling pressure in the pressure lock section, in which the sealing units can be selectively and sequentially moved from the sealed position to the retracted position to allow introduction of an item therethrough, and in which the pressure lock section is selectively pressurizable or depressurizable to allow the item to move from low to high or high to low pressure during injection or removal.   
     
     
         2 . The apparatus of  claim 1  wherein the tubular length is coiled tubing, slickline or wireline. 
     
     
         3 . The apparatus as claimed in  claim 1 , wherein a diameter of the pressure lock section is greater than or equal to the diameter of a hole or pipeline being injected into. 
     
     
         4 . The apparatus of  claim 1 , wherein the item comprises a tool, a sensor, a centralizer or a skate. 
     
     
         5 . The apparatus of  claim 4  wherein the centralizer comprises a quick-connect system. 
     
     
         6 . The apparatus of  claim 4  wherein the centralizer includes an axial restraint means. 
     
     
         7 . The apparatus of  claim 4  wherein the centralizer comprises or includes clamp means for clamping onto or around a tube, pipe, or cable. 
     
     
         8 . The apparatus of  claim 4  wherein the centralizer comprises two ends and one of the two ends provides axial restraint. 
     
     
         9 . The apparatus of  claim 1  further comprising an automatically attachable and detachable skate for a tube, pipe, or cable intended to be injected into a downpipe or pipeline. 
     
     
         10 . The apparatus of  claim 9 , wherein the skate comprises two or more parts that can be clamped together on or around a tube, pipe, or cable. 
     
     
         11 . The apparatus of  claim 9  wherein the skate uses one or more of ratchets, bayonets, springs and magnets to attach on or around a tube, pipe, or cable. 
     
     
         12 . The apparatus of  claim 9  further comprising an apparatus for automatically attaching and removing the skate. 
     
     
         13 . A method of injecting or removing items into or from a pressurized downhole, pipeline when carried on or by a tubular length, the method comprising the steps of:
 a. providing two or more sealing units that seal against the length as the item is injected;   b. providing a pressure lock section which joins the sealing units;   c. moving a first, earlier sealing unit to a retracted position while a second, later unit is in a sealed position;   d. moving the item through the earlier sealing unit and into the pressure lock section;   e. closing the first sealing unit;   f. equalizing the pressure in the pressure lock section with the pressure beyond the later sealing unit;   g. moving the later sealing unit to a retracted position to allow the item to pass therethrough; and   h. moving the later sealing unit to a sealed position.   
     
     
         14 . A method as claimed in  claim 13 , further comprising the steps of:
 i. depressurizing the pressure lock section; and   j. moving the upstream sealing unit to a retracted position.   
     
     
         15 . A method of removing items from a pressurized downhole, pipeline when carried on or by a tubular length, the method comprising the steps of:
 providing two or more sealing units that seal against the length as it is withdrawn;   providing a pressure lock section which joins the sealing units;   moving a first, earlier sealing unit to a retracted position while a second, later unit is in a sealed position;   moving the item through the earlier sealing unit and into the pressure lock section; closing the first sealing unit;   equalizing the pressure in the pressure lock section with a lower pressure beyond a later sealing unit; and   moving the later sealing unit to a retracted position to allow the item to pass therethrough.   
     
     
         16 . The method of  claim 15  further comprising providing an automatically attachable and detachable centraliser for a tube, pipe, or cable intended to be injected into a downpipe, or pipeline. 
     
     
         17 . The method of  claim 16  wherein the centraliser comprises two or more parts that can be clamped together on or around a tube, pipe, or cable. 
     
     
         18 . The method of  claim 16  wherein the centraliser uses one or more of ratchets, bayonets, springs and magnets to attach on or around a tube, pipe, or cable. 
     
     
         19 . The method of  claim 15  further comprising providing a machine handlable chassis for detachably attaching items on a tube, pipe, cable intended to be injected into a downpipe or pipeline. 
     
     
         20 . The method of  claim 19  wherein the chassis uses one or more of ratchets, bayonets, springs and magnets to attach on or around a tube, pipe, or cable. 
     
     
         21 . The method of  claim 19  wherein the chassis is, forms part of or allows attachment of a centraliser, a tool, a sensor, or a skate. 
     
     
         22 . A method for determining a required position and spacing of centralisers or skates along an injectable tube, the method taking into account one or more of the following criteria:
 predicted final position;   well and pipeline profile;   number of, position and tightness of bends, length of inclined/horizontal sections,   well pressure profile along the well trajectory,   well fluid and gas properties,   well and pipeline inner diameter,   CT/Slickline or Wireline outer diameter and thickness   detail on possible tapering wall thickness of CT,   well temperature profile along the well trajectory, and   injection speed.