Development of slurries and study of properties of cement mixtures to increase the quality of well completion

Physical and mechanical properties of polymer cement slurries and cement stone are studied. The goal of the work is to improve the quality of completion of productive formations by development of polymer cement mixtures with improved structural and mechanical characteristics of a cementing slurry and cement stone. During the completion a special attention is paid to the preservation of well cement stone quality. So, there is a brittle fracture of the cement stone occur because of the dynamic loads caused by cumulative and bullet perforation, as well as the torpedoing of casing strings. Using such methods of well completion a cement stone can be destroyed both in perforation intervals and in places of bridges that separate productive layers from aquifers. The consequence of that opening is the accelerated growgh of water cut of wells. Despite the high technical level of new types of perforators, they are not widely used in drilling of oil and gas wells because of the large time and metal consumption of the work performed and, consequently, high financial costs of their use. It is known that the integrity of the cement stone is ensured at perforation during the transition of the coagulation structure of a cement suspension to crystal one. For a normal cement slurry (water/cement = 0.5) that moment occurs relatively quickly (7-15 h), which is not enough for perforation operations. In order to modify the properties of a cement mixture the compositions of cation-active surfactant (catamine) and non-ionic polymer (polyvinylpyrrolidone) were chosen. Results of experimental studies show that the input of these agents into the composition of a cement mixture leads to an increase in spreadability of a cement slurry (more than 25 cm by the cone of Azerbaijan Scientific Research Institute), time of its bondability, strength of a cement stone for compression (200 % after 28 days of hardening) and bending (250 %), adhesion of cement stone to metal (by 80 %) and time of coagulation structure setting. In addition, plastic properties of the developed cement slurry are retained for more than 19 hours. The influence of the agent (defoamer T-66) on the rate of cement stone strengthening is determined. It is shown that input of a nonionic high molecular polymer reduces the rate of the formation of crystal structure in a cementing mixture