Abstract: A flexible drill string for curving a vertical borehole laterally towards the horizontal, comprising an elongated flexible casing made of a plurality of sections with each section having a longitudinal central axis. Each section is attached to an adjacent section such that the casing string can conform to a segment of a curve. An elongated flexible drilling string is rotatably received within the flexible casing and an annulus is formed between the casing and drill string. The drill string has a central fluid passageway of resilient material surrounded by a plurality of longitudinally extending bendable members that jointly encapsulate the central fluid passageway and forms an outer housing about the drill string. The drill string central passageway is an elastomeric conduit and the plurality of bendable members are placed circumferentially thereabout and are connected together to form the housing.

Abstract: A training apparatus by which situations liable to occur during drilling for oil and gas, such as a blow out, may be simulated to teach better control thereof. The apparatus comprises a miniature drilling rig, a transparent bore hole casing imitation and a pressurized oil/gas reservoir imitation sealed from the casing by an easily through-drilled plug in the lower end of the casing.

Abstract: A screen with a solid arylene sulfide polymer-polytetrafluoroethylene coating is provided that is suitable for use in a solids separating device. The poly(arylene sulfide)-polytetrafluoroethylene coating provides efficient passage of semi-solid or gummy material across the screen surface thereby reducing the chance of blinding the screen. Method of separating drilling mud.