METHOD OF FABRICATION OF ELECTRIC BAFFLE FOR DRILLING SPRINGS Russian patent published in 2008 - IPC E21B47/12 

FIELD: petroleum industry.

SUBSTANCE: invention relates to oil and gas production industry and is intended for fabrication of electric baffles (EB). Conical thread is cut on the couple and connector parts of EB, next the parts connected are sand blasted, degreased and coated with composite dielectric material (CDM). Then parts of EB are threaded up through CDM, a dielectric insert (DI) is mounted inside EB and a layer of CDM is applied on its exposed surface. EB is fabricated by pressure moulding with application of a mould made of rubber, sealants or CDM by the winding on method. Thread is cut over CDM that forms the dielectric liner. DI inside EB is made in the shape of a fluoroplastic pipe, which is inserted inside EB through the sealing rings, fixed from either side by metal bushes and sealed. Water is injected under pressure of 20-30 MPa into the internal space of EB plugged at the ends so as to remove air out of DI through the full-length bore drilled preliminarily in the connector of the couple part of EB; next the bore is welded up without releasing pressure in the internal space of EB. The conic thread is delta shaped with rounded angles or round-shaped to prevent formation of stress concentrators in the thread.

EFFECT: increased strength and reliability of the electric baffle of the drilling string.

2 cl, 1 dwg