Research On Low-density Cement Slurry System In Medium And Deep Wells In Zhangwu Area

Northeast oil and gas branch company exploring oil and natural gas in Zhang Wu area began in the late 1980s, and has obtained the breakthrough in 2011, by now has proven reserves of 30 million tons of oil resources in Zhang Wu region. The depth of Vertical Wells is about 2000 meters, the region of the reservoir are mainly concentrated in Shahai group and nine Buddhist Temple group, it has a low formation pressure coefficient, is a typical low pressure formation easy to leakage in Zhang Wu area. In order to solve this situation, using the density of 1.50g/cm3 low density cement slurry system and way of two stage cementing to prevent the leakage when cementing, but still cannot solve the region cementing problem of reservoir leakage, it brings about many adverse effects to the cementing quality and the production for Zhang Wu region?This paper comprehensive Zhang Wu area of cost control and the low density cement slurry cementing reservoir, consider the cement slurry has a lowering density in 1.25g/cm3?1.35g/cm3 to solve the problem of cementing leakage in the region. Firstly, the paper starts with the material of cement slurry system in Zhang Wu area, using the existing materials to solve the cementing leakage problems of the region. Evaluation results of materials system in Zhang Wu area:because of the cost control in the region, the material system performance is poorer, the density of floating bead is 0.92 g/cm3, results in the decrease of density is difficult; The stability of cement slurry can be adjusted when the density of cement slurry is 1.35g/cm3, but the 24 hours of compressive strength cannot meet the requirements; When the slurry density drops below 1.35g/cm3 cement slurry system stability problem is not adjustable?In Zhang Wu area of low density cement slurry system and cementing status, the optimal method of ultra low density reducing agent, mitigate the agent density is 0.47g/cm3, and optimizing the high-performance filling agent, can effectively reduce the cement slurry solid ratio, not only improve the gel component content in slurry, the compressive strength and the density of cement are improved, and the production cost is well controlled. Through the optimization of the early strength agent with better effect, it can ensure that the cement slurry has a high early strength under the condition of consistency. The comprehensive performance of low density cement slurry system has been evaluated in the paper.In this paper, successfully developed a density of 1.25 g/cm3?1.35 g/cm3 and can satisfy the cycle temperature 50??-70? of low density cement slurry system. The system has the advantages of good settlement stability and rheological properties, low API filtration, the advantages of early strength development and good comprehensive performance. The low density cement early strength development fast, dense internal structure, low permeability, elastic modulus than conventional low density cement has been effectively reduce, it can effectively improve the cement ring air isolation ability, with independent research and development laboratory simulation experiment of high temperature and high pressure cement ring complete device. And through the exchange of late tracking, the optimize the system of low density cement slurry in Northeast oil and gas company has been popularized and applied, it effectively preventing the leakage and oil, gas and water channeling, improve the cementing quality of wells with low pressure and easy leakage, for save drilling cost and improve the efficiency of oil and gas exploration and development to provide technical support.