Content introduction

1. Causes of cement sheath seal failure

2. Toughening principle of cement paste

3. Evaluation parameters and methods of toughened cement

4. Experimental analysis of cement stone deformation

1. Causes of cement sheath seal failure

1.1 overview

(1) Cementing quality plays an important role in prolonging the life of oil and gas wells and enhancing oil recovery.

(2) At present, domestic conventional well and complex well cementing, oil and gas water channeling and interface cementing quality problems have not been well solved. One of the reasons is that the existing cement slurry system has insufficient deformation capacity of cement stone. In the follow-up construction process, such as perforation, late production, fracturing, acidizing, etc., the cement sheath is impacted and vibrated, and the cement sheath is broken on the one hand, and on the other hand, the cement sheath is broken On the one hand, the cementation with casing or well wall is partially invalid, which can not maintain long-term effective interlayer sealing during oil well production.

(3) In particular, side drilling cementing, small gap annulus cementing and gas storage cementing

The hardness and brittleness of cement paste is the main reason that causes the integrity of oil well cement sheath to be damaged in the complex downhole conditions and the subsequent construction of oil and gas wells, resulting in the failure of interlayer sealing.

Therefore, it is necessary to improve the mechanical properties of oil well cement paste, endow oil well cement paste with certain elastic and plastic deformation ability, increase the impact crushing resistance of cement paste, reduce the fracture degree caused by the stress concentration of cement sheath under the impact force or alternating force, and the damage degree of the integrity of oil well cement sheath in the later construction, so as to maintain the integrity of cement sheath and realize long-term stability The effective interlayer sealing can improve the production life of oil and gas wells or the working life of gas storage.