Abstract: The invention is concerned with the design of oil wells by defining a number of design parameters, some of which are interdependent. The invention makes use of successive optimizations. Input data are selected for a first parameter and varied to achieve a first optimization. The process is repeated for a second parameter whose input data includes the first parameter, and then repeated for each other of the defined parameters. The design parameters may be presented to the user via a graphical interface such as a virtual reality view.

Abstract: Drilling apparatus includes an inclined mast, a drive carriage slidably mounted on the mast for rotating a tubular drilling member, and at least two positioning units secured to the mast at spaced positions therealong for positioning tubular drilling members. Each positioning unit has a frame which can be raised a preset distance above the mast and lowered from the preset distance. Grippers adjacent opposite sides of the frame can be raised a preset distance above the frame and lowered from the preset distance. The grippers can be moved towards one another to grip a tubular drilling member therebetween and moved away from one another to release the tubular drilling member. Locators adjacent opposite sides of the frame can be raised to cause the locators to engage and position lower parts of the tubular member, with the tubular member being movable away from the mast out of contact with the locators without moving the locators. The drive carriage is movable along the mast past at least one positioning unit.