Application of high-density and low-friction cement slurry system in the Gaoshiti Block

Abstract:

The Gaoshiti Block faces multiple challenges during the cementing of ?177.8 mm liners， including active oil and gas shows， high pumping pressure， a narrow window of safe density， susceptibility to lost circulation， and significant wellbore temperature variations. These conditions impose strict requirements on the density control， rheology， and stability of the cement slurry. To enhance the performance of high-density cement slurry， a high-density， low-friction system with an adjustable density （2.1~2.4g/cm3） was developed. This was achieved by optimizing a compound weighting agent consisting of micromanganese spherical particles and iron ore powder， in combination with a low-viscosity fluid-loss additive and a polymer suspension stabilizer. The system demonstrates excellent high-temperature stability and pumpability， effectively reducing friction and improving annular displacement efficiency. Field applications in four wells within the block showed a reduction in pumping pressure by 4~6MPa， an increase in annular displacement efficiency to over 90%， a cementing qualification rate exceeding 70%， full returns to the planned depth， and no fluid losses across the entire interval. The theoretical friction pressure closely matches field measurements， confirming the system’s adaptability and engineering feasibility， and providing strong support for its broader application in the Gaoshiti Block.