Abstract: A well testing system is described which comprises a ball valve (10) having a plurality of fluid lines coupled thereto (20a, 20b, 20c). The ball valve (10) is located between a process fluid flow line (16) and a vent line (18) with each fluid line (20a, 20b, 20c) being coupled to a respective piece of well-test equipment rated at a certain pressure value. Pressure relief means (22a, 22b, 22c) are located in each fluid line (20a, 20b, 20c) between the piece of equipment and said ball valve (10) and each pressure relief means (22a, 22b, 22c) is operable when the in-line fluid pressure exceeds a predetermined value to pass said fluid to said ball valve (10).

Abstract: A pressure relief valve includes an apertured ball valve element which is spring loaded and is rotatably and axially mounted in the valve bore so that when an over pressure situation arises fluid forces the ball axially off the valve seat against the force of a spring and causes the ball valve to rotate such that the aperture in the ball valve connects the inlet bore and outlet bore of the valve housing so that fluid can flow through the pressure relief valve. When pressure at the inlet falls beneath a predetermined value, the spring forces the ball to rotate and move back against the valve seat, thus closing the valve. With this arrangement there is minimal pressure exerted on the valve housing and the valve will operate with a back pressure up to 50% of the inlet pressure. This means that much smaller bore outlet piping can be used with a savings in weight and, consequently, cost.

Abstract: A tubing test valve (34, 34a) is described for use with a drill string (20) for pressure testing tubulars and downhole equipment, particularly in a cased hole (12) which has a permanent packer (16) fitted. The valve (34) permits self-filling during running-in, but allows pressure testing when stationary in the well (1). The valve (34) also permits multiple entry of the string to, and retrieval from, permanent packers without committing the tool to the locked open position. This is achieved by providing an apertured ball valve (50, 50a) in the tool housing (42, 42a) which can be moved axially and rotated with the bore (70A, 71A) of the housing (42, 42a). The ball valve has side orifices (54, 54a) and a top orifice (52a) which controls flow through the valve (34, 34a). In one embodiment the ball element (50) is suspended by coil spring (64) above the lower valve seat (56) during running-in and is closed for pressure testing by pressuring with fluid from above.