In the construction of the conductor casing and surface casing cementing, due to the low bottom hole circulating temperature(BHCT), the compressing strength of oil well cement development slowly, waiting on cement(WOC)need a long time, an increase of drilling costs, could easily lead to annular gas channeling, and have a bad effect on cement job quality and safety of operations. For the type of current domestic oil well cement early strength agent are few, The effective of some early strength agent are not satisfied. Some are Corrosive to the casing, and have a great influence on slurry rheology and other issues. Laboratory selected a new compound early strength agent with on chlorine and containing crystal seed.The thickening time, compressive strength, settlement stability properties, anti-gas channeling ability and other parameters of the slurry are tested. The results show that: There are some advantages of the cement slurry like right-angle-set, low temperature rapid strength, excellent settlement stability properties, and strong ability of anti-gas channeling and form a low density cement slurry which density range from 1.30 to 1.90g/cm3, it provide a reliable guarantee to cementing operation in shallow well with low-temperature under the different reservoir pressure.

Usually, marine carbonate gas reservoirs contain formation water with high content of CO2&H2S, It is difficult to satisfy the requirement of cementing quality in the gas reseroirs exploration due to the corrosion effect of formation water on cement. In this thesis, corroding tests of cement in formation water, which derived from a development well in northeast Sichuan province, were based on the simulation environment condition of 90°C under 0.1 MPa, 5 MPa and 10Mpa. Performances of cement including mineral composition, microstructure and permeability before and after corrosion were measured by TG-DTA, SEM, XRD and gas permeability and porosity of dense rock core tester. The results show that main corrosion products of cement being corroded in formation water with high content of CO2&H2S are ettringite, CaCO3 and CaSO4, both strength reduction and gradual rising of permeability can occur as testing pressure increasing. Accordingly, the corrosion mechanism and the damage process of cement under formation water with high content of CO2&H2S are expounded in the end.

The influences of KCl on the performance of G-Grade oil-well cement are discussed in this article. The macro performances including the rheological property, filter loss of slurry and the thickening time, strength and shrinkage of cement are tested. And the reasons why those influence could happen are explained by analyzing the microscopic structure of the cement. The results show that: KCl takes participation in hydration reaction of cement, KAlSiO3 and Ca4Al2H0.34O6.34Cl1.67 are generated in the reaction that could improve the compressive strength of the cement and reduce the shrinkage of the cement, but there is a limited added amount, less than 12% (BWOW) is the best.

During shale gas well drilling and completion, the oil based muds (OBMs) would reduce the bonding strength of cement slurry by filter-cake and oil-wettability. At the same time, mixing cement slurry with the OBMs can lead to contamination, and subsequently creates significant problems, such as, reducing the normal thickening time and the compressive strength, and hence affecting the quality of the cementing of the shale gas well. Therefore in the present investigation, the mechanism of the interface displacement, wetting conversion and the contamination was explored by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), scanning electron microscope (SEM) and other methods. And then the new materials with the enhanced bonding strength and the contamination relieving by OBMs were obtained. The results showed that the chemical composition of filter-cake determined the properties of chemical preflush, the combined systems (LSS) efficiently flushed filter-cake and increased the bonding strength. It has been found that the reverse wetting agent (APG) has better reverse wetting properties than Tarim Oilfield current application system, which effectively changes the wettability of cementing surface from lipophilicity to hydrophilic. The OBMs and cement slurry mixing generated the emulsion structure and honeycomb structure, and the structures can affect the rheology and the strength of cement slurry; the contaminative relieve agent (SCW) can form a thin film on the surface of the cement stone, the film covers the hole and improves cement compressive strength, thus the SCW can relieve the contamination by OBMs.

The multi-cycle recovery of heavy crude oil thermal by steam injection and stimulation has serious effects on the integrity of cementing sheath. At present, the class G oil well cement with silica sands, less resistant to high temperatures, does not meet the quality of the heavy crude oil well cementation and requirements of recovery and production. The laboratory results show that Aluminates cement has the characteristics of high early strength; meanwhile, it can maintain strength and stability in a long-term under the circulation of high and low temperature conditions. However, its hydration product C3AH6, which makes it a sharp recession in intensity at low temperature, limits its application. According to the clinker selection and compounding with the main item of Aluminates cement indoor experimentation, there comes out a new type of cement binder which generates C3ASH4 and other stable phase within rounds of high and low temperature cueing, and made the crystal structure of cement in dense arrangement. With this method, cement hydration structure can be maintained with a long-term stability; and it has the value of further development.