1. The purpose and significance of studying latex toughener

The cement stone made of pure oil well cement for cementing is brittle material with low tensile strength and flexural strength. Under low tensile deformation, microcracks will appear on the cement stone. Then when the external load continues to increase to a certain value, the microcracks on the cement stone will rapidly expand into macro cracks. When the crack is large, the cement sheath may lose alignment The sealing effect of oil and gas wells leads to channeling of oil and gas intervals, which seriously affects the development and transformation of oil wells after perforation. If the toughness of cement stone does not meet the requirements, it will lead to cement sheath fragmentation and the decline or even ineffectiveness of the first interface and the second interface, which will cause the oil and gas fluid and the fluid between the formation to flow into the annulus between the oil well and the formation, resulting in the failure of interlayer segmentation. So far, we can only take measures such as squeezing cement to make up for it, but it will inevitably lead to oil and gas The cost of well cementing increases greatly, and the production life of oil and gas wells is bound to be seriously affected. One of the main reasons for the above problems is that the toughness of cement stone is too low, resulting in insufficient mechanical deformation. In cementing operation, the external forces that cause cracks or even fragmentation of cement sheath are mainly in the following aspects:

(a) In the process of drilling, the cement sheath between wellbore and casing will be impacted by the rotating drill string and bit;

(b) In high angle and horizontal well cementing, the cement sheath between wellbore and casing also bears the action of larger shear force and tensile force during drilling and production.

(c) In perforating oil and gas wells and subsequent stimulation measures, cement sheath will also be subject to great impact, vibration and internal pressure.

Therefore, improving the mechanical properties of cement paste, reducing the brittleness of cement paste, endowing oil well cement paste with good toughness, increasing its mechanical deformation ability, improving the anti impact crushing performance of cement sheath, and reducing the damage degree of cement sheath rupture caused by stress concentration when the cement sheath is subjected to impact force can prolong the production life of oil and gas wells and improve the recovery factor It plays a very important role.