低热水泥浆用微胶囊型热控材料制备及应用

Preparation and Application of Microencapsulated Thermal Control Materials for Low Hot Cement slurry

摘要:

深水低温高压环境下，水合物层普遍存在，深水表层套管固井时水泥浆水化放热，容易使天然气水合物层分解，导致地层失稳，给深水固井带来极大风险。本文基于天然气水合物低温、高压及电解质条件下的分解特性，以常规波特兰油井水泥为基料，外掺入自主研发的微胶囊型热控材料PCM-1，成功研发了一种低水化热水泥浆体系。采用自研半绝热测试实验设备对水泥浆体系早期水化过程中温度进行了连续测量，以水泥浆体系最高温度(Tm)及最大水化温升(Tr)表征了对水化热控制效应。实验结果表明，PCM-1加量15%时，该水泥浆较纯水泥浆. 水化最高温度下降了21.1 ℃，最大水化温升下降了23.6 ℃；24 h及48 h水化热分别下降了7.68 ? 104 J及7.28 ? 104 J。该项技术可实现对水泥浆水化温升及水化热的有效控制，大幅降低深水水合物层的固井风险。

Abstract:

Hydrate layers are common in deep water environment with low temperature and high pressure. During surface casing cementing, hydration and heat release of cement slurry in deep water is easy to decompose natural gas hydrate and lead to formation instability, which brings great risks to deep water cementing. Based on the decomposition characteristics of natural gas hydrate at low temperature, high pressure and electrolyte, a low-hydration hot cement slurry system was successfully developed, with Portland oil well cement as the base material and the addition of self-developed micro-capsule type thermal control material (PCM-1). In the early hydration process of the cement slurry system, the temperature was continuously measured by self-developed semi-adiabatic test equipment, and the hydration heat control effect was characterized by the maximum temperature (Tm) and the maximum hydration temperature rise (Tr) of the cement slurry system. The results showed that compared with pure slurry cement system, hydration maximum temperature decreases by 21.1℃, when 15 wt% PCM-1 was added. At the same time, the maximum hydration temperature rise decreased by 23.6℃. In addition, 24 h and 48 h hydration heat respectively decreased by 7.68?104 J and 7.28?104 J. This technique can effectively control the hydration temperature rise and hydration heat of cement slurry, greatly reducing the cementing risk of hydrate layers in deep water.