The British Petroleum Company, P.l.c.

Prem Sagar Thukral

Brian Peter Goldie

Ronald Alfred Crump

Richard A Cayless

William C Pike

Martin A Bollands

Timothy P Woolmington

A drill shoe adapted to fit onto a drill pipe of external diameter d.sub.e and internal diameter d.sub.i comprises an externally stepped cutting surface comprising a plurality of steps, the diameters of the steps increasing as they progress away from the tip of the shoe. The maximum external diameter D.sub.e of the shoe is greater than the external diameter d.sub.e of the drill pipe. The shoe also comprises an internal, substantially cylindrical, inner surface of diameter D.sub.i, D.sub.i being less than the internal diameter d.sub.i of the drill pipe. The shoe is suitable for use in a vibratory drill string for obtaining cores from unconsolidated geological formations, such as soil, sand and gravel or similar materials.

Drill shoe

A method of inhibiting corrosion of a metal surface comprises applying to the metal surface an organic solvent in which is dissolved a phosphate monoester of a hydroxyalkyl acrylate or a hydroxyalkyl alkylacrylate which phosphate monoester has the general formula; ##STR1## where R.sub.1 is hydrogen, a methyl group or an ethyl group R.sub.2 is an alkyl group having from 2 to 10 carbon atoms and

Surface treatment of metal

Process for making a catalyst precursor by heating an inorganic oxide support with a titanium compound at a temperature in the range 150.degree. to 1200.degree. C and then retreating with titanium one or more times by alternately adding a hydroxyl compound (e.g. water) and titanium compound and heating at 150.degree. to 1200.degree. C. The precursor can be used to make a useful ethylene polymerization catalyst by adding a chromium compound and heat activating at a temperature in the range 100.degree. to 1200.degree. C.

Polymerization catalyst

Process for preparing a supported Ziegler catalyst precursor by heating together, at a temperature in the range 150.degree.-1000.degree. C, an inorganic support having surface hydroxyl groups and a magnesium compound selected from the oxide, hydroxides, salts and alkoxides and incorporating a transition metal compound therein.

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Kenley, United Kingdom

Prem Sagar Thukral