钻井液侵入时水合物近井壁地层物性响应特征

发布时间：2018-05-16 21:28

本文选题：天然气水合物 + 实验模拟　；参考：《地球科学》2017年03期

【摘要】：目前,国内外学者对钻井液侵入水合物地层的室内实验模拟研究停留在较小尺度上且可靠性难以验证,尚需利用与实际地层物性参数较为贴近的沉积物模型,开展大尺度的实验模拟,为改善水合物地层钻井过程中钻井液工艺和测井准确识别与评价水合物储层提供依据.根据墨西哥湾水合物地层主要物性参数指标压制了相应的人造岩心,进行了人造岩心钻井液侵入实验.结果表明:水合物在加热分解过程中,温度与压力呈上升趋势,而电阻率先升高后下降,水合物相平衡条件不仅与温压条件有关,还受孔隙水盐度不断变化的影响。钻井液侵入岩心过程中,压力的传递速率快于热量的传递,易使原始岩心孔隙中的水、气在压力升高而温度尚未改变的情况下生成二次水合物.钻井液温度是水合物分解的主要因素,而压差有利于提高孔隙水压力,保持水合物的稳定.高密度钻井液虽有利于形成高压差和抑制水合物在钻井液中形成,但也会导致钻井液低侵并使井周水合物更易分解.因此,在实际水合物地层钻井中,为了减少钻井安全事故,应在安全密度窗口范围内尽可能提高钻井液密度,选用温度较低的钻井液并加入一定量的动力学抑制剂或防漏失剂.电阻率测井应该选用随钻测井方式或者深侧向测井值,从而避免因水合物分解导致的测井失真.
[Abstract]:At present, the laboratory simulation study of drilling fluid intruding into hydrate formation by domestic and foreign scholars remains on a small scale and difficult to verify, so it is necessary to use the sediment model which is close to the physical parameters of the actual formation. Large-scale experimental simulation is carried out to provide the basis for improving drilling fluid technology in hydrate formation drilling and accurate identification and evaluation of hydrate reservoir by logging. According to the main physical parameters of hydrate formation in the Gulf of Mexico, the corresponding artificial core is suppressed, and the intrusion experiment of artificial core drilling fluid is carried out. The results show that the temperature and pressure of hydrate increase in the process of heating and decomposition, while the resistance increases first and then decreases. The phase equilibrium condition of hydrate is not only related to the temperature and pressure, but also affected by the changing salinity of pore water. In the process of drilling fluid intruding into the core, the pressure transfer rate is faster than the heat transfer, and the water in the pore of the original core and the gas can form the secondary hydrate under the condition that the pressure increases but the temperature does not change. The temperature of drilling fluid is the main factor of hydrate decomposition, and the pressure difference is helpful to improve the pore water pressure and maintain the stability of hydrate. Although the high density drilling fluid is beneficial to the formation of high pressure difference and the inhibition of hydrate formation in the drilling fluid, it can also lead to the low invasion of drilling fluid and make the hydrates around the well more easily decomposed. Therefore, in order to reduce the drilling safety accidents, the drilling fluid density should be increased as much as possible in the range of safe density window in the actual hydrate formation. The drilling fluid with low temperature should be selected and a certain amount of dynamic inhibitor or leakage prevention agent should be added. In order to avoid logging distortion caused by hydrate decomposition, logging while drilling or deep lateral logging should be used in resistivity logging.
【作者单位】：中南大学有色金属成矿预测与地质环境监测教育部重点实验室;中南大学地球科学与信息物理学院;中国地质大学工程学院;国家海洋局第二海洋研究所;
【基金】：国家自然科学基金项目(Nos.40974071,51274177,41502346) 湖北省自然科学基金重点项目(No.2012FFA047) 中国地质大学(武汉)中央高校基金项目(Nos.CUGL100410,CUG120112,G1323511453);中国地质大学(武汉)实验技术项目(No.CUGL140819) 中南大学有色金属成矿预测与地质环境监测教育部重点实验室开放基金资助项目(Nos.2016YSJS005,2016YSJS011)
【分类号】：TE254

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