FORMATION TREATMENT

Sand in unconsolidated subterranean formations causes problems in oil recovery, which can be overcome by a method of consolidating sand in a subterranean formation, which method comprises: (i) contacting said sand in a first location in the presence of water with a slurry in a liquid medium of cement of average particle size less than 10 microns to produce in said medium a mixture comprising sand, water and some of the cement, and a remainder comprising the rest of the cement, (ii) preferably separating from said location said remainder from said mixture, (iii) which mixture is allowed to set to give permeable consolidated sand.