低渗特低渗油层富气—氮气复合驱  

Rich gas-nitrogen compound flooding in low and ultra-low permeability layers

作　　者：陈涛平[1] 毕佳琪 孙文 赵斌 CHEN Taoping;BI Jiaqi;SUN Wen;ZHAO Bin(Key Laboratory of Enhanced Oil and Gas Recovery,Ministry of Education,Northeast Petroleum University,Daqing,Heilongjiang 163318,China;Oil Recovery Plant No.3,PetroChina North China Oilfield Company,Renqiu,Hebei 062552,China)

机构地区：[1]东北石油大学提高油气采收率教育部重点实验室,黑龙江大庆163318 [2]中国石油华北油田分公司采油三厂,河北任丘062552

出　　处：《东北石油大学学报》2020年第4期40-47,I0004,共9页Journal of Northeast Petroleum University

基　　金：国家科技重大专项(2017ZX05009-004)。

摘　　要：为提高低渗、特低渗油层富气—氮气复合驱采收率,以YS油田的特低渗油层为背景,采用CMG油藏数值模拟软件建立细管理想模型,研究富气组分对最小混相压力的影响及富气—氮气在油气相中的分布;利用条状均质和非均质模型,研究油层长厚比、渗透率、渗透率级差及富气段塞尺寸因素对驱油效果的影响;选用30 cm长度的低渗、特低渗2类天然岩心,分别进行5种方案的物模实验研究。结果表明:富气中CH_4体积分数越高,富气与原油的最小混相压力越大,注入CH_4体积分数低、富化程度高的富气有助于提高原油采收率;细管中富气段塞至少有0.50 PV才能有效阻止氮气窜逸对采收率的影响;油层渗透率越低或渗透率级差越小,越有利于提高复合气驱采收率,厚度小于井距2%的油层也有利于提高复合气驱采收率;富气—氮气复合驱合理的前置富气段塞尺寸为0.60 PV,低渗和特低渗岩心的采收率分别为65.91%和73.21%,接近于全富气驱采收率;在五点法井网条件下,富气—氮气复合驱中富气的合理段塞为0.60 PV,低渗和特低渗油层的采收率分别为51.46%和50.88%。该结果可以为开发低渗特低渗油层提供指导。In order to improve the recovery of low and ultra-low permeability layers by rich gas-nitrogen compound flooding,the ultra-low permeability reservoirs in YS Oilfield is taken as the background.CMG reservoir numerical simulation software was used to establish a slim pipe model,studied the rich gas composition on the influence of the minimum miscible pressure and the distribution of rich gas and nitrogen in the oil and gas phase.Using strips in homogeneous and heterogeneous model,we studied length-thickness ratio,permeability,permeability level difference,and rich gas slug size on oil displacement effect.The 30 cm long low-permeability and ultra-low permeability natural cores were selected and the physical model experiments of 5 schemes were carried out respectively.The results show that higher the content of CH 4 in rich gas,the larger the minimum miscible pressure of rich gas and crude oil,as far as possible inject the rich gas with low content of CH 4 and high degree of enrichment,help to improve the recovery.In the slim pipe model,the rich gas slug should have at least 0.50 PV to effectively prevent the impact of nitrogen escape on recovery.The lower the layer permeability or the smaller the permeability level difference,the more conducive to improving combination recovery.Layers with thickness less than 2%from well spacing are also conducive to enhanced recovery.The reasonable preposition rich gas slug size of rich gas-nitrogen compound flooding is determined to be 0.60 PV.At this time,the recovery of low permeability and ultra-low permeability cores are 65.91%and 73.21%,close to the recovery of full rich gas flooding.Under the condition of five-point well pattern,the reasonable slug of rich gas in rich gas-nitrogen compound flooding is 0.60 PV,and the recovery are 51.46%and 50.88%respectively.The results can provide guidance for the development of low and ultra-low permeability reservoir.

关 键 词：低渗透油层 特低渗透油层 富气驱 氮气驱 富气—氮气复合驱 

分 类 号：TE348[石油与天然气工程—油气田开发工程]