Study and Application of a Fly Ash-slag Bonding Reinforcement Material

When using a low-density cement slurry to cement a well, several problems need to be addressed, such as low early strength, deviation in compatibility with cement and high operation cost. To solve these problems, studies were conducted on fly ash and slag for their chemical composition, specific surface area and micromorphology using XRF, XRD and SEM etc. The study results have shown that the particle sizes of the fly ash and slag are distributed mainly in ranges of 0.36 – 89.34 μm and 1.56 – 39.91 μm, respectively, the specific surface area of the fly ash and the slag is 0.822 m²/g and 1.79 m²/g, respectively. The particles of these two materials have smooth surfaces and are closely packed. By analyzing the working mechanisms of the reinforcement materials, some organic and inorganic reinforcement materials were selected, taking the compressive strength of the flay ash cement slurry as the primary technical indicator. The optimum ratios and concentrations of these materials in the final reinforcement material were determined through laboratory studies as follows: 35%KZ+8%FMH+ 8%WK+3%NY+2%NS+6%CS. An alkali-activated fly ash-slag compound bonding reinforcement material was developed. The reaction process, micro structure and compressive strength of the alkali-activated fly ash-slag compound bonding reinforcement material in the QZ and FMH cement slurries were studied. Evaluation of the general performance of the bonding reinforcement material showed that when the concentrations of the bonding e reinforcement material in these two cement slurries are 10% and 9% respectively, the property of the cement slurries is able to meet the requirements of field operations. The bonding reinforcement material has been used in 7 well/times and the well cementing quality was 100% certified, achieving the expected goals.