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随着勘探领域不断向深部油气藏拓展，固井遭遇的复杂井越来越多。为了进一步加强粉煤灰低密度水泥浆体系在低压易漏复杂地层固井中的应用，经过大量室内研究，开发出以海泡石为主要成分的新一代稳定剂SSD，碱性有机物质类早强激活剂TSN，室内评价了它们在粉煤灰水泥浆体系中的性能，配制出密度可在1.30~1.45 g/cm3之间可调的粉煤灰复合低密度水泥浆体系。实验结果表明，该水泥浆体系的流动性好、析水率小、失水可控、稠化时间可调，水泥浆凝结后的水泥石不但抗压强度高，而且还具有一定的体积膨胀率，能完全适用低压易漏地层固井的要求，并保证水泥环与地层、套管间的良好胶结，提高固井质量。另外，粉煤灰、微硅使水泥石具有良好的抗腐蚀能力，海泡石、微硅等使水泥浆具有一定的触变性，这说明该水泥浆体系能兼有多种特性，是一种能满足复杂井固井需要的低密度水泥浆体系。

Research on Low-density Cement Slurry System for Complex Well Cementing

Along with oil and gas exploration's being expanded into deep-burial strata,the complex well cementing jobs arc getting more and more. In order to strengthen the application of the low-density ash-fly cement slurry system in the well cementing of low pressure lost-circulation zones,the new generation of stabilizing agent being mainly composed of sepiolite (SSD) and the early strength activator of alkaline organic matters (TSN) were developed through a great number of laboratory researches; and the ash-fly compound low-density cement slurry system with adjustable densities of 1. 30-1. 45 g/cm3 was made up on the basis of evaluating the functions of SSD and TSN in the slurry system. According to the experimental results, it was indicated that this slurry system has these properties, such as good flowability, small watcr-scperating rate, controllable water loss and adjustable thickening time,and its bond cement is of not only high compression strength but also a certain volume expensivity, so that it can fully meet the needs of the well cementing of low pressure lost circulation zones and can ensure a good bonding between cement sheath and casing/wall, thus raising cement job quality. In addition, the ash-fly and hyperfinc silica can make the bond cement possessing good corrosion resistance and the sepiolite and hyperfine silica can cause the cement slurry possessing a certain thixotropy, which shows that this slurry system can meet the needs of complex well cemeting, being of multiple-property.