Downhole wellbore treatment system and method

A downhole wellbore treatment system for treating an inner surface of a wellbore, the system comprising:

• an elongate conduit having a central longitudinal axis for conveying treatment fluid from the surface to a treatment head adapted to be inserted into the wellbore,
• the treatment head having a central longitudinal axis and a first outlet nozzle and a second outlet nozzle providing an outlets from the conduit for creating a jet of treatment fluid directed at the inner surface of the wellbore,
• wherein the treatment head is rotationally disconnected from the conduit by a swivel device, allowing rotation of the head relative to the conduit during jetting of the treatment fluid,
• wherein the treatment head comprises said first and second outlet nozzles and a flexible hose and the said first and second outlet nozzles are connected to the conduit by the flexible hose,
• wherein the system incorporates a turbine assembly which comprises the said swivel device and a turbine disposed in fluid communication with the conduit and the treatment head,
• wherein the treatment head is connected to the turbine assembly by the said flexible hose such that the treatment head is in fluid communication with the conduit via the turbine assembly whereby flow of fluid through the conduit drives the turbine to rotate the treatment head relative to the conduit;
• wherein the treatment head further includes at least one radial thrust nozzle, wherein the force of the pressure of the treatment fluid within the elongate conduit exiting the radial thrust nozzle is operable to thrust the treatment head off the longitudinal central axis of the elongate conduit and thus forces the first and second outlet nozzles toward the inner surface of the wellbore,
• wherein the first outlet nozzle is an aperture formed through a sidewall provided on one side of the treatment head and the radial thrust nozzle is an aperture formed through a sidewall provided on a second side of the treatment head, and wherein the second outlet nozzle is an aperture formed at the leading, most downhole, end of the treatment head and which is angled from the longitudinal central axis of the treatment head in the direction of the first outlet nozzle, and
• wherein the elongate conduit is reelable and is inserted into the downhole wellbore from a reel at the surface, through a pressure control device containing wellbore pressure within the downhole wellbore during insertion of the elongate conduit from the reel.