REVERSE CIRCULATION DIRECTIONAL AND HORIZONTAL DRILLING USING CONCENTRIC COIL TUBING

摘要

Method and apparatus for drilling a directional or horizontal wellbore in a hydrocarbon formation using concentric coiled tubing drill string (03) having an inner coiled tubing string (01) and an outer coiled tubing string (02) defining an annulus (30) there between. A bottomhole assembly (22) comprising a directional drilling means (04) is provided at the lower end of the concentric coiled tubing drill string for reverse circulation drilling. Directional drilling means comprises a reciprocating air hammer (80) and a drill bit (78), a positive displacement motor and a reverse circulating drill bit, or a reverse circulating mud motor and a rotary drill bit, and a bent sub or housing. Drilling medium is delivered through the annulus or inner coiled tubing string for operating the directional drilling means to form the directional or horizontal wellbore.