低密度高强度水泥浆体系在苏丹1/2/4区块的应用

苏丹1/2/4区块中的4区面积较1区和2区大，是地层较复杂的区块，此区块的Zarap、Betinue和Baraka等层位地层压力系数低，固井施工中易发生水泥浆漏失，造成低返；地层成岩性差，易发生井塌，糖葫芦现象严重，固井施工中顶替效率低。并且这一区块的井普遍较深，封固段较长。苏丹1/2/4区块位于北纬5°～10°之间，天气炎热，年平均气温高，地温梯度高，给固井施工带来很大的困难。文章从地层资料、井身结构、固井工艺等环节进行分析、研究，经过大量的室内试验和现场应用，确定出性能优良的低密度高强度水泥浆体系，解决了该地区固井技术难题。

APPLICATION OF CEMENT SLURRY SYSTEM WITH LOW DENSITY AND HIGH STRENGTH IN BLOCKS 1/2/4 OF SUDAN 1)

Among the blocks 1/2/4 of Sudan, the area of Block 4 is bigger than that of Blocks 1/2. The formations are complicated in Block 4. The formations of Zarap, Betinue and Baraka etc. in the block have low formation pressure coefficient so that the cement slurry leaking often happen, which makes the cement slurry not reaching the design highness in the cementing process. The formations have poor diagenesis and the collapse of bore walls happens easily, which makes the borehole very irregular and the replacing ratio low in the cementing job. Usually, the wells in the block are deep and the interval to be cemented is long. The blocks 1/2/4 of Sudan are located between 5° and 10° of north latitude, where the weather is hot, the yearly average temperature is high, and the geothermal gradient is high, which brings big difficulty to the cementing operation. With study and analysis for the formation information, the borehole structure, and the cementing techniques etc, going through many in house tests and field applications, it is found the high quality cement slurry system with low density and high strength. Therefore, the technical problem of well cementing in the area is solved.