METHOD FOR DRILLING AND LINING THE WELLBORE AND DEVICE FOR ITS REALIZATION Russian patent published in 1995 - IPC

FIELD: well drilling and lining. SUBSTANCE: method includes lowering of drilling tool down to bottom hole, well drilling, supply of grouting material through drill pipe string and formation of lining. Lining is alternated with drilling. Drilling is effected by means of folding rock cutting tool. After drilling, tool is lifted to wellhead through drill pipe string. Drill pipe string is preliminarily filled with fluid. Then, drilling mud is supplied to drill pipe string-wellbore annulus. Density of mud exceeds that of fluid. Grouting material is used in form of thermoplastic material which is melted on bottom hole. Well lining is formed with similar flow area through well depth. Device for realization of method includes drill string, retrievable lining unit and rock cutting tool. It is made in form of cylinder with recesses on inner side surface and axial channel which is closed with spring-loaded valve. Device has bit-reamer made in form of at least three folding roller bits, one of which is rigidly connected with rod located under ball valve. Two other roller bits are installed for motion along axis of cylinder over its recesses. Attachment unit has heating chamber with electric heating elements. Attachment unit also has limiter of upward motion and is made in form of rod with electromagnetic drive. Cables are found on outer surface of drill string. EFFECT: higher efficiency. 2 cl, 14 dwg