Properties and application of oil-well cement enhanced with a novel composite toughening agent

Abstract

Brittle fracture of cement sheath, induced by perforation and stimulation treatments, can cause cross flow of formation fluid and increase casing damage. A novel agent XL was developed for solving the problem. Experimental results showed that the toughness of the set cement containing XL was improved remarkably. The engineering properties of the slurry containing XL, drag reducer USZ (0.2% BWOC), filtrate loss additive F17B (1.2% BWOC) and crystalloid expanding agent F17A (3% BWOC) could meet technical requirements of cementing operation. After perforation, good quality cement sheath enhanced with XL was observed by CBLNDL logs in a deep well.

Analysis and countermeasures on sustained casing pressure in b-annulus of shale-gas horizontal wells in Sichuan basin of china

“…Meanwhile, in order to effectively reduce the plastic deformation of cement stone, it is necessary to reduce the porosity of cement stone effectively and restrain the microscopic and macroscopic defects of cement stone. [5][6][7][8][9][10] A low elastic modulus and low porosity cement slurry system was designed, with the basic formula as follows: JHG+(2-8)% organic elastic material+(8-15)% non-base nanoemulsion+(2-3) % fluid loss additive+(2-3)% expansion agent+(0.1-0.5)% retarder+(1-2)% nonbase toughener+44% water. The density of cement slurry formed was 1.88g/cm 3 , the permeability of cement stone was 0.02mD, and the porosity was 25.5%-27.8%, which was 27.1% lower than that of the conventional cement stone; the API water loss was less than 36 mL, the free fluid was 0, the 48 h compressive strength was greater than 12 MPa, and the initial consistency was less than 22Bc.…”