Abstract: An embodiment of a PCD insert comprises an embodiment of a PCD element joined to a cemented carbide substrate at an interface. The PCD element has internal diamond surfaces defining interstices between them. The PCD element comprises a masked or passivated region and an unmasked or unpassivated region, the unmasked or unpassivated region defining a boundary with the substrate, the boundary being the interface. At least some of the internal diamond surfaces of the masked or passivated region contact a mask or passivation medium, and some or all of the interstices of the masked or passivated region and of the unmasked or unpassivated region are at least partially filled with an infiltrant material.

Abstract: A method of separating oil, water and sand in a production fluid. The production fluid is fed through a downhole liquid/liquid hydrocyclone (9). An oil enriched stream from the hydrocyclone (9) is pumped to the surface, while an oil depleted stream is fed to a downhole solid/liquid hydrocyclone (12). Here, the bulk of the solids is separated from the water, so that water which is substantially free of solids can be transported to a downhole disposal site (14).

Abstract: Downhole apparatus for separation of oil from oily water or water from oil having an internal chamber continuously flooded with production fluids from a well, one or more hydrocyclonic separators for separating the production fluid into a stream enriched in oil and an stream depleted in oil. The clearance required between the apparatus and the well casing being the minimum required for running the apparatus into the casing, maximizing the size of the separator(s) and improving capacity. A range of artificial lift devices is included to bring the oil enriched stream to the surface if the natural pressure of the reservoir is insufficient. Substantial axial overlap of multiple separators is provided for better compactness and capacity of the apparatus. Pipes from separator overflow outlets connect to a common overflow manifold, and pipes from the separator underflow outlets connect to a common underflow manifold.

Abstract: A method and apparatus for subjecting a fluid to a controlled pressure drop. Fluid is supplied under pressure with a tangential velocity component to an annular passageway (17). The fluid swirls around the axis of the passageway while flowing axially along the passageway to an outlet (6). A cross section of at least a part of the passageway (17) is adjustable to enable the flow rate to be adjusted for a given pressure loss or the pressure loss to be adjusted for a given flow rate. The outlet (6) includes a second annular passageway (22) surrounding the first annular passageway so that the first annular passageway leads to, and the second annular passageway leads from, a chamber (21) common to the passageways. The second annular passageway is of increasing outer diameter and cross sectional area in the direction of flow from the chamber to the outlet.