Patent ID: 6065209
Filing Date: 2000-05-23
Classification: E21B,Y10T

Abstract:
A method of fabrication of a leak-proof multi-lateral casing/liner branch tubular connector, from metal blank tubular casing and liner elements having outer and inner wall surfaces, prior to their inclusion in a casing string of casing elements and prior to the cementation of said casing string into a borehole, comprising the steps of:inserting and positioning a blank tubular casing element within a re-usable rigid tubular corset with said rigid tubular corset and said casing element having a common longitudinal axis, said tubular casing element having upper and lower ends protruding from said rigid tubular corset, said rigid tubular corset presenting a corset window having a window edge and dimensions slightly greater than the dimensions of a casing window cutout required for making a tight casing/liner connection at a specified kick-off angle, said rigid tubular corset also having a plurality of spaced and oriented small holes located outside of said corset window,firmly holding said blank tubular casing element in co-axial cylindrical position with and within said rigid tubular corset by a plurality of fastening means cooperating with said small holes in said rigid tubular corset for transmitting compressive forces from said rigid tubular corset to said outer wall surface of said tubular casing element,inserting a multi-purpose stiffening internal in said tubular casing element, said internal including a guiding channel for directing a branch tubular connector liner element at said specified kick-off angle from said tubular casing element, precisely positioning said internal across a depth interval of said tubular casing element with respect to said corset window, affixing said internal to said inner wall surface of said tubular casing element by a plurality of drillable fastener as a structural reinforcement offsetting the anticipated reduction in strength resulting from cutting an elongated casing window into said tubular casing element, said internal providing dual channel inlets at one end of said internal including at least one by-pass flow channel for fluids and cement slurries in said tubular casing element across said depth interval covered by said internal,accurately cutting said casing window cutout into and through said tubular casing element inner and outer wall surfaces by means of a cutting tool guided by said guiding channel to produce a windowed tubular casing element having an accurately cut surface at said edge of said casing window cutout, said cutting tool being guided in part by said window edge of said corset window,inserting a liner element into said casing window cutout,machining at least one end of said liner element to achieve a close fit of said machined end of said liner element with said accurately cut edge surface of said casing window cutout,plugging-off said casing window cutout with a drillable ribbed cover plate stiffener shaped to materialize the double curvature, in space, of said casing window cutout,equipping the upper and lower ends of said tubular casing element protruding from said rigid tubular corset with fastening means capable of providing a leak-proof connection between said windowed tubular casing element and adjacent casing elements of a casing string,releasing said compressive forces applied from said rigid tubular corset to the outer surface of said windowed tubular casing element,and removing said plurality of fastening means between said rigid tubular corset and said windowed tubular casing element outer surface to allow the extraction of the completed casing/liner branch tubular connector from said rigid tubular corset.