密闭取心技术的新发展

胜利油田经过30多年的注水开发,老区地下情况发生了很大的变化,综合含水不断上升,使密闭取心效果越来越差,直接影响到增产挖潜措施的制定。从1995年开始,对特高含水、特高渗透率、特疏松地层进行密闭取心技术攻关,将保形取心工具和密闭取心工具合二为一,组成新的保形密闭取心工具。采用防钻井液污染岩心的取心钻头、优质WHC-3密闭液、优质钻井液和平衡压力钻井技术等措施,试验7口井,取心进尺485.10m,岩心收获率93.77%;累计分析取样2131块,岩心密闭率达到85%,对开发后期残余油饱和度与驱油效率的分布及变化规律,以及油层物性、孔隙结构及其它地层物理特征变化规律有较好的认识,从而为增产挖潜、改善水驱效果提供了地质依据。

ADVANCES IN SEALED CORING TECHNOLOGY

The underground of old areas in Shengli oilfield changed a lot after waterflooding for more than 30 years. Ever-increased water cut made the effectiveness of sealed corlng worse and worse, this directly influenced the stipulation of stimulation. The sealed coring technology for extra-high water content, extra -high permeability and extra - unconsolidated formations has been studied since 1995. Combining conformal coring tools with sealed coring tools formed new conformal sealed coring tools. Using coring bits which can prevent cores from drilling fluid, high grade WHC-3 sealant, high grade drilling fluid, balanced pressure drilling technology and so on, 7 wells were experimented. The coring footage was 485. 10m, the core recovery was 93. 77%, 2131 rock samples were analyzed and thecore sealing rate amounted to 85%. This helped to know well about the distribution and principles of residual oil saturation and oil displacement efficiency, the physical properties ofoil reservoir, pore structure and geological features. This provided geological basis for stimulation and improvement of waterflooding effectiveness.