Microstructure formation and degradation mechanism of cementitious plugging agent slurries

Abstract

The hydration products and microstructure of class G oil well cement and a newly developed plugging agent (YLD) slurries cured in the simulated temperature and pressure environment, which was of similar temperature and pressure with those at the bottom of oil well in a normal depth, were investigated using XRD, TG and SEM. Severe leakage is confirmed at the interface between hardened slurries and steel tube during the dynamically curing process, which induces the quick loss of cementing property of slurries. This should be the dominating cause of degradation of class G oil well cement slurry. A secondary hydration process can take place at the eroded interface of hardened YLD plugging agent slurry. Newly formed C-S-H gel has a self-healing effect to repair the damaged interface, which unceasingly maintains the cementing property of the YLD plugging agent slurry. Therefore, the effective using period of YLD plugging agent can be prolonged.

Keywords

oil well cement / YLD plugging agent / microstructure / degradation / leaching

References

[1] B Wang, Y X Cheng, Y X Jian, Z M Hu. Study on Synthetical Relieving Plug Agent for Steam Huff-puff Wells in the Watersensible Formation[C]. Proceeding — SPE International Symposium on Oilfield Chemistry, 1995: 701–714

[2] Liu Q. P., Hou S. J., Ha R. H., Zhang S. J. Study on a High Strength Oil Field Water Plugging Agent[J]. Petrochemical Technology, 1995, 24(8): 557-560.

[3] M G R Bosma, E K Cornelissen, P M T Reijrink, et al. Development of a Novel Silicone Rubber/Cement Plugging Agent for Cost Effective Thru’ Tubing Well Abandonment[C]. Proceeding of the IADC/SPE Asia Pacific Drilling Technology Conference, 1998: 483–496

[4] D Quinn, E Sunde, J F Baret. Mechanism of a Novel Shear-sensitive Plugging Fluid to Cure Lost Circulation[C]. Proceeding — SPE International Symposium on Oilfield Chemistry, 1999: 227–231

[5] G Fuh, N Morita, P A Boyd, S J McGoffin. New Approach to Preventing Lost Circulation While Drilling[C]. Proceedings-SPE Annual Technical Conference and Exhibition v Delta, 1992: 569–582

[6] D T Mueller, G DiLullo, J K Hibbeler. Portland Cement-blast Furnace Slag Blends in Oil Well Cementing Applications. Proceedings-PE Annual Technical Conference and Exhibition Delta, 1995: 659–662

[7] Yang Z. J., Li M. G., Guo J. H., . Recondition of Injury Casing with Plugging Sgent in Oil and Water Injection Wells[J]. Oil Drilling and Production Technology, 2001, 23(4): 68-71.

[8] Taylor H. F. W. Cement Chemistry, 1997 2 London: Thomas Telford.

[9] S Diamond. Cement Paste Microstructure-An Overview at Several Levels[C]. Proceedings of a Conference on Hydraulic Cement Paste: their Structure and Properties, Sheffield, 1976