固井水泥浆对储层损害的再认识

Re-recognition of cement slurry damage to reservoir

固井作业是油气田开发过程中的重要一环,其对储层的损害主要由水泥浆滤液造成且是永久性的。储层损害程度与水泥浆滤液组分和侵入范围有关,射孔完井时孔眼长度是否大于滤液侵入深度,直接关系到水泥浆对储层的损害程度和油气井后续产量。通过分析水泥浆对储层的影响,提出了一种根据固井施工设计参数计算水泥浆滤液最大侵入深度的方法。该方法所需参数容易获得,计算简便,考虑了水泥浆动态和静态滤失阶段的极限滤失情况,可作为射孔完井时射孔深度设计的参考,对油气井储层保护和射孔完井参数设计具有重要意义。一般来说,采用密度1.9 g/cm^3的水泥浆对砂岩储层进行固井时,水泥浆滤液侵入储层深度在常规射孔范围内,水泥浆对储层的污染可以忽略不计。

Cementing operation is a prominent stage in oil and gas field development. The damage of formation caused by the slurry filtrate is permanent. The invasion range and components of cement slurry filtrate have a great relationship with reservoir damage, especially during the process of perforation completion. Whether the hole length is greater than the invasion depth or not is directly related to the formation damage and subsequent production of oil and gas wells. This paper presents the analysis of the effect of cement slurry on the reservoir, and a method used to calculate the maximum penetration depth of cement slurry using the design parameters of cementing operation was obtained. The calculation method considers the maximum filtration loss in both dynamic/static conditions. The needed parameters can be easily obtained and the calculation process is simple. The calculated cement slurry filtrate invasion depth can be used as a reference for perforation depth design during completion perforating, as well as it has great significance to formation protection of oil and gas wells and the design of perforation completion parameters. In general, when cement slurry with a density of 1.9 g/cm^3 is used for cementing the sandstone reservoir, the invasion depth of filtrate in reservoir is within the range of conventional perforation and the contamination of the cement slurry can be ignored.