Abstract:
Objective To dispose and utilize pyrolysis residues of oil-based drilling cuttings (PRODCs) during exploitation of shale gas safely and effectively, original ceramic proppants were first prepared by sintering the pellets using PRODCs as a raw material. In order to improve the suspension performance of the proppants in water and the distribution of proppants in cracks so as to simplify the fracturing process and enhance the effect of increasing production, the surface characteristics of this ceramic proppant was modified to achieve self-suspending.
Methods Polypropylene amine resin was used to coat the surface of proppant by aqueous graft polymerization during the modification. The effects of the content of crosslinker and monomer as well as the synthetic temperature on the properties of polymer-coating proppants were discussed.
Results When the weight ratio of ceramic proppants, acrylamide, N, N′-methylene bisacrylamide, ammonium persulfate and N, N, N′, N′-tetramethylethylenediamine was controlled at 10.000∶2.000∶0.002∶0.020∶0.0310 respectively, the prepared self-suspended proppants could achieve optimal self-suspending performance with swelling ratio of 4.3 and settling velocity of 45 mm/s.
Conclusions The realization of self-suspending function for proppant is related to swelling of polyacrylamide. During the modification process, the settling resistance is brought by the expansion of polymers and viscosity increase of solution due to the extension of molecular chain of polyacrylamide. It is of great importance to enhance the functional properties of ceramic proppants with PRODCs and increase the additional value in the recycle utilization of the wastes.
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