The Effect of Opal-Containing Rocks on the Properties of Lightweight Oil-Well Cement

Abstract

When constructing deep wells for oil and gas production in difficult geological conditions, special lightweight oil-well cements are used. To reduce the density and water separation of the cement slurry as well as to increase the strength, corrosion resistance of cement stone and the quality of well cementing, opal-containing rocks, fly ash, microsphere and other lightening additives are introduced into the cement composition. The influence of sedimentary rocks, such as opoka, tripoli, and diatomite containing from 43 to 81% amorphous silica on the grindability, rheological and physical-mechanical properties of lightweight oil-well Portland cement has been studied. The twelve cement compositions with different content of additives (from 30 to 45%) that meet the requirements of the standard for density, spreadability, water separation, thickening time and flexural strength were selected. The introduction of 45% diatomite or tripoli significantly reduces the duration of cement grinding, provides the cement slurry with water-cement ratio of 0.9 with better density and flexural strength, respectively, 1480 kg/m3 and 1.1–1.5 MPa.

Obtaining a silicon alloy from a sedimentary rock - tripoli

“…t. of tripoli -a loose or weakly cemented finely porous sedimentary rock consisting of radiolarian skeletons with an admixture of clay minerals, glauconite, quartz, feldspars [5,6]. Tripoli contains 73 -86 % of SiO 2 , the main part of which is amorphous silica [7,8]. Tripoli is mostly (by 75 %) used in the cement industry, agriculture (as a mineral feed additive, organic fertilizers), construction (production of foam glass, heat and sound insulation materials), for purification of water, oil products, manufacture of paper and cardboard, detergents and cleaning products, insect repellents [9 -13].…”

Electrothermal production of ferroalloy from tripoli

“…Therefore, silica in tripoli is mainly in an amorphous state, a characteristic feature of which is an increased reactivity in comparison with the crystal form [4]. Using this property of amorphous silica, in contrast to the known methods of its application [ [5], [6], [7], [8], [9], [10]], it was proposed to use tripol as a silicon-containing raw material to produce a siliceous ferroalloy [11] for the smelting of which quartzite is used [ [12], [13], [14], [15]]. The article presents the results of studies to determine the optimal parameters for the electrothermal production of silicon ferroalloy from tripoli.…”