耐高温高压超高密度水泥浆体系的室内研究

天湾1井是位于准噶尔盆地中部的一口超深预探井，井深为7500 m，井底压力为170 MPa，井底温度为160℃，针对该井高温高压的问题，以及目前超高密度水泥浆存在的流动性和沉降稳定性差、动态失水量较大、以及大温差下顶部水泥石强度出现过缓凝等问题，室内成功研制出耐高温高压超高密度水泥浆体系，水泥浆密度可达2.55 g/cm3，该体系主要由新型加重剂、微硅、高温稳定剂、600目硅石粉（粒径为0.025 mm）、新型微锰矿粉、悬浮剂、高温缓凝剂、高温降失水剂、高温减阻剂等组成。实验结果表明，该体系水泥浆流动度达到32 cm，同时具有较好的沉降稳定性能，顶部水泥石强度较高，防气窜能力强，在160℃、170 MPa下，稠化时间线性可调，动态失水量为40 mL，该水泥浆体系应用范围广泛，可通过调整外加剂掺量来满足天湾1井不同井深温度下的固井施工要求。 

Laboratory Study on an HTHP Ultra-High Density Cement Slurry

The well Tianwan-1 is an ultra-deep exploration well located in the middle of the Junggar Basin, with depth of 7,500 m, bottom hole pressure of 170 MPa and bottom hole temperature of 160 ℃. A high temperature high pressure ultra-high density cement slurry was developed in laboratory to overcome the high temperature and high pressure, as well as the other problems related to ultrahigh density cement slurries, such as poor fluidity, poor settling stability, high dynamic fluid loss, and over-retarding of the strength of the top set cement under big temperature differences, etc. The highest density of the cement slurry was 2.55 g/cm3. The cement slurry was developed with a new weighting agent, micronized silica, a high temperature stabilizer, powdered silica passing through 600-mesh screen, a new micronized manganese powder, a suspending agent, a high temperature retarder, a high temperature filter loss reducer and a high temperature friction reducer. Laboratory experimental results showed that the cement slurry had fluidity of 32 cm, good settling stability, high strength of top set cement and strong capacity of anti-channeling. The thickening time of the cement slurry is linearly adjustable at 160 ℃ and 170 MPa. Dynamic filter loss of the cement slurry was 40 mL. The cement slurry can be used in a wide range of downhole conditions; by changing the concentrations of the different additives, the cement slurry can satisfy the needs of cementing operation at different downhole temperatures (hence different depths) in the well Tianwan-1.