羽状水平井欠平衡钻井环空流动特性研究  

STUDY ON ANNULAR FLOW PERFORMANCE OF PINNATE HORIZONTAL WELL BY UNDER-BALANCED DRILLING

作　　者：张义[1] 鲜保安[2] 周卫东[3] 孙粉锦[1] 任源锋 

机构地区：[1]中国石油勘探开发研究院廊坊分院,河北廊坊065007 [2]中国地质大学工程技术学院,北京海淀100083 [3]中国石油大学石油工程学院,山东东营257061 [4]中国石油渤海钻探井下作业公司,河北廊坊065007

出　　处：《西南石油大学学报（自然科学版）》2010年第3期117-121,共5页Journal of Southwest Petroleum University(Science & Technology Edition)

基　　金：国家煤层气"973"项目(2009CB219607);国家科技重大专项子课题(2008ZX05033)

摘　　要：羽状水平井欠平衡钻井技术是近几年来国内外煤层气开发中普遍采用的一项减少储层伤害、提高低渗储层煤层气采收率的新技术。针对该技术的技术特征,建立了物理模型和数学模型,结合现场井例分析了井筒环空内各流动特性参数的变化规律。结果表明:井底压力随泥浆排量的增加单调递增,同一泥浆排量条件下,环空注气量越大,井底压力值越低;羽状井自注气点至井口的井筒环空内,水平段由于静液压力占主导,空隙率、混相流体流速增长幅度较小,混相流体密度少许降低,压降损失也较少;竖直井筒环空内空隙率及混相流体流速自井底沿井筒向上初始缓慢增大,当环空压力降低到一定程度后,由于气液滑脱效应,而急剧增大,环空内混相流体密度变化规律与之相反,环空压力自井底沿井筒向上呈线性减小。Under-balanced drilling technology for pinnate horizontal well is a new technology that has been widely used for enhancing the coal bed methane recovery of low permeability reservoirs and reducing the coal seam damage both home and abroad.In this paper,based on the characteristics of this new technology,the physical model is established,the mathematical models are optimized,and the solution to the models is also proposed.With the established models and the field case,by calculating and analyzing the bottom hole annular flow performance and annular gas-injection parameters,the authors conclude that the bottom hole pressure increases as the mud discharge rate increases.The larger the annular gas injection rate is,the lower the bottom hole pressure at the same mud discharge rate.The air voids and the fluid velocity in vertical well bole annulus increase slowly from the bottom to wellhead at first,but fall rapidly when the annular pressure drops to a certain extent,which is contrary to the distribution of the density of annular miscible liquid.The annular pressure decreases linearly from the bottom to wellhead.

关 键 词：煤层气 羽状水平井 欠平衡钻井 流动特性 环空压降 井底压力 环空注气量 

分 类 号：TE242.9[石油与天然气工程—油气井工程]