火烧吞吐井用抗高温耐腐蚀水泥浆体系

火烧吞吐采油技术是近年来发展很快的一种具有明显优势和潜力的热力采油方法,其特殊的采油工艺需要开发一种同时具有抗550℃以上高温和耐CO₂腐蚀性能的水泥浆体系。从水泥石耐高温和抗腐蚀机理出发,研发了一种磷铝酸盐水泥GWC-500S,该水泥通过对铝酸盐水泥加入磷酸盐、氧化铝粉、耐腐蚀材料、激活材料等进行改性而得,同时研发了配套的多元单体聚合的液体降失水剂GWF-500L及无机酸缓凝剂GWR-500S,并配制出了适用于火烧油层固井的水泥浆体系。对50、300和600℃不同温度下水泥石进行XRD实验,分析了不同温度下水泥水化产物和水化产物随着温度变化的情况;对600℃煅烧后水泥石剖面进行了扫描电镜分析;对磷铝酸盐水泥经过550℃高温煅烧7 d后的强度变化进行了评价;在120℃、CO₂分压约为6.9 MPa条件下,对水泥石耐CO₂腐蚀性能进行了评价。研究结果表明,该体系具有在40~100℃范围内稠化时间可调,API失水量小于50 mL,水泥浆流变性能良好等特点,且该水泥石可耐550℃高温强度不衰退、抗CO₂腐蚀性能良好、密度可调、稠度适中、稳定性良好,与钻井液、隔离液相容性良好。该水泥浆在××油田火烧油层吞吐试验区块英试×井进行了试验应用,经室内实验和现场应用证明,其满足火烧油层固井工艺要求。 

High Temperature Corrosion Resistant Cement Slurry Used in Fire Soaked Well Cementing

Fire soaking production is an advantageous thermal production technology fast developed in recent years. This technology requires cement slurry to have the thermal stability above 550℃ and resistance to CO2 corrosion, such as GWC-500S, a phosphoaluminate cement which was developed by adding phosphate, alumina powder, corrosion resistant agent and activator into an aluminate cement. A liquid filter loss reducer GWF-500L and an inorganic acid retarder GWR-500S have also been developed for use in the cement. A cement slurry was developed with these materials and the set cement was tested using XRD at 50℃, 300℃ and 600℃. Hydrates of the cement and their changes with temperature were analyzed. Set cement calcinated at 600℃ was analyzed using SEM for its profile. Changes in the strength of the phospho-aluminate cement after calcination at 550℃ for 7 d were evaluated. Resistance to CO2 corrosion of set cement at 120℃ and a CO2 partial pressure of 6.9 MPa was evaluated. It is understood through these studies and evaluations that the phospho-aluminate cement slurry has thickening time adjustable between 40℃ and 100℃, API filter loss of less than 50 mL, and good rheology. The set cement has the advantages such as:resistance to high temperature to 550℃, resistance to CO2 corrosion, adjustable density, moderate thickness, good stability, and good compatibility with drilling fluids and spacers. The cement slurry has been successfully tried on well Yingshi X in a fire soak test block in XX oilfield. Laboratory experiments and field application prove that the phospho-aluminate cement slurry satisfies the needs for fire soak well cementing.