气体示踪在非均质特低渗透油藏二氧化碳驱气窜监测中的应用

APPLICATION OF CO2 CHANNELING MONITORING FOR USING GAS TRACER IN ULTRA-LOW-PERMEABILITY RESERVOIRS CO2 FLOODING

延长靖边油田乔家洼区是CO2捕集、埋存与提高采收率示范(CCUS)的先导试验区,属于特低渗透油藏,非均质性强,在气驱过程中易发生气窜,降低CO2驱开发效果。为更好实施气窜监测,掌握气窜特征和规律,文章通过气体示踪剂背景浓度分析及配伍性实验筛选确定采用SF6作为监测示踪剂,同时研究合适的注入用量,通过现场实施,对注采井组连通关系、受效方向、示踪剂突破时间及气驱推进速度进行研究,再利用示踪剂解释对气窜的优势通道即高渗带的厚度、平均渗透率及平均孔道半径等有关参数定量计算。文章形成一套系统的陕北特低渗透油藏CO2驱气相示踪剂监测方法,为CO2驱油方案调整提供一定的依据,有助于提高CO2驱整体开发效果。

The Qiaojiawa district of Yanchang Jingbian Oilfield is the pilot test area for CO2 capture,storage and enhanced oil recovery(CCUS)demonstration which belongs to ultra-low-permeability reservoirs.Gas channeling is easy to occur during gas flooding,reducing carbon dioxide flooding development.For implementing of gas channeling monitoring to understand the characteristics and laws of gas channeling,In this paper,SF6 was selected as the monitoring tracer through background concentration analysis of gas tracer and compatibility experiment,and the appropriate injection dosage was studied.Through on-site application,the relationship between injection and production wells,direction of effect,tracer breakthrough time,and gas drive propulsion speed were studied.Using tracers to explain the quantitative calculation of relevant parameters such as the thickness,average permeability and average pore radius of the dominant channel of hyperventilation.This article forms a systematic monitoring method for CO2 flooding tracer in ultra-low-permeability reservoirs in northern Shaanxi,which provides a certain basis for adjustment of CO2 flooding scheme and helps to improve the overall development effect of CO2 flooding.