Development of composition of cementing slurry for fastening of low-cemented rocks

Abstract

Purpose. Improving the producing capacity and ensuring the stable operation of gas wells that develop unstable, low-cemented reservoirs by preventing the sand entry from the reservoir by means of creating the cement stone with the corresponding values of strength and permeability in the bottomhole formation zone. Methods. The technological characteristics of the cementing slurry and the formed cement stone are measured using standard recording equipment. The cementing slurry consistency is measured with a pycnometer, the cement mixture spread ability – using AzNII cone, water separation is measured according to standard methods (DSTU BV.2.7 – 86-99), and the time of the cementing slurry hardening is determined on a consistometer KTS-3. The ultimate parameters of the stone strength during bending are determined on a special device for testing linear objects in tension, and compression – on a PSU-10 hydraulic press. Findings. The cementing slurry composition for creating the cement stone with the corresponding values of compression strength and gas permeability in the bottomhole formation zone has been developed, which includes oilwell cement, expanded perlite, non-ionic surfactant, plasticizer and water. Dependences of the cement stone compression strength and the stone permeability coefficient on the proportion of expanded perlite in the cementing slurry solution have been revealed. It is recommended to use the proposed cementing slurry for creating a cement stone with specified values of compression strength and permeability in the expanded well shaft in the interval of the producing reservoir. Originality. The optimal proportion of the expanded perlite in the solution has been found, at which the corresponding values of the compression strength (up to 4 MPa) and gas permeability (up to 3.47 μm2) of the cement stone is provided. Practical implications. When using the developed composition, it is possible to increase the yield of wells with unstable reservoirs and improve their working conditions by preventing the sand entry from the reservoir into the well.