Abstract: There is disclosed an apparatus for axially anchoring a tool downhole in a well casing, the apparatus comprising: an anchor configured to be disposed in, and actuatably and rotatably engaged with, the casing; and a rotatable tool being configured to be disposed within the casing; whereby the anchor, when rotatably engaged with the casing, prevents movement of the rotatable tool in the axial direction A whilst allowing for rotation of the tool about the axial direction. A corresponding method of anchoring a tool downhole is also disclosed.

Abstract: There is provided a method of assessing the quality of subsurface position data and wellbore position data, comprising: providing a subsurface position model of a region of the earth including the subsurface position data, wherein each point in the subsurface position model has a quantified positional uncertainty represented through a probability distribution; providing a wellbore position model including the wellbore position data obtained from well-picks from wells in the region, each well-pick corresponding with a geological feature determined by a measurement taken in a well, wherein each point in the wellbore position model has a quantified positional uncertainty represented through a probability distribution; identifying common points, each of which comprises a point in the subsurface position model which corresponds to a well-pick of the wellbore position data; deriving for each common point a local test value representing positional uncertainty: selecting some but not all of the common points and deri

Abstract: A method of forming a geological model of a region of the earth includes obtaining seismic data relating to the region, the seismic data including seismic traveltime uncertainty. A seismic velocity model of the region may also be provided and includes velocity uncertainty. Ray tracing may be performed on the seismic data using the velocity model to determine the three dimensional positions of a plurality of points of the region. The three dimensional positional uncertainties (7-12) of at least some of the points can be calculated from the traveltime uncertainty, the velocity uncertainty, and uncertainty in the ray propagation direction. This can be combined with the positions determined by the ray tracing to form a geological model.

Abstract: A method of forming a geological model of a region of the earth includes obtaining seismic data relating to the region, the seismic data including seismic traveltime uncertainty. A seismic velocity model of the region may also be provided and includes velocity uncertainty. Ray tracing may be performed on the seismic data using the velocity model to determine the three dimensional positions of a plurality of points of the region. The three dimensional positional uncertainties (7-12) of at least some of the points can be calculated from the traveltime uncertainty, the velocity uncertainty, and uncertainty in the ray propagation direction. This can be combined with the positions determined by the ray tracing to form a geological model.