吉木萨尔页岩油长裸眼井油基钻井液防塌技术
Oil-Based Drilling Fluid Anti-Collapse Technology for Long Openhole Wellbore of Jimsar Shale Oil
吴义成 1刘鹏 1曹青天 1常会盼 1李帅 1张斌1
作者信息
- 1. 中国石油西部钻探工程有限公司 钻井液分公司,新疆 克拉玛依 834000
- 折叠
摘要
吉木萨尔页岩油长裸眼段水平井采用二开井身结构,二开裸眼段长达4 000 m,水平段超2 000 m,钻井液采用油基钻井液,钻进中在八道湾组、韭菜园子组等地层易出现井壁垮塌现象,从而引发钻具遇阻、遇卡、井漏等事故.为解决复杂地层的井壁垮塌问题,根据地层岩性特征,分析了地层黏土组分、微裂隙发育等影响井壁失稳的主要因素,明确了易垮塌地层的井壁失稳机理,提出了油基钻井液的"多元协同、广谱封堵"防塌理论.基于防塌理论,优选了沥青、超细碳酸钙、纳米封堵剂等材料完善了油基钻井液防塌配方,室内实验显示,钻井液密度1.52～1.62 g/cm3、马氏漏斗黏度80～100 s、动切力8～13 Pa、破乳电压500 V以上、油水比80∶20～85∶15、120℃高温高压(HTHP)滤失量≤2 mL,钻井液各项性能参数均满足施工要求,且封堵效果良好.该油基钻井液防塌体系在吉木萨尔页岩油长裸眼段水平井上成功应用,裸眼段平均井径扩大率3.03%,事故复杂时效0.55%,有效保证了造斜段、水平段的钻井安全.
Abstract
The horizontal well of Jimsar shale oil with a long openhole wellbore adopts the two-casing-section structure,and the open-hole wellbore of the second casing section is 4 000 m long,with a horizontal wellbore over 2 000 m.The used drilling fluids are oil-based,and wellbore collapse tends to occur when drilling the Badaowan and Jiucaiyuanzi Formations and leads to movement resis-tance,sticking of tools,lost circulation,etc.To overcome the wellbore collapse in complex formations,in accordance with the lithologi-cal characteristics of formations,the main factors affecting wellbore stability such as clay mineral composition and micro-fracture de-velopment were analyzed,the mechanisms of wellbore instability of such collapse-prone formations were clarified,and the anti-col-lapse theory of oil-based drilling fluids was developed,which features"multi-element cooperation and broad-spectrum plugging".Based on the proposed theory,the anti-collapse formulation of oil-based drilling fluids was improved by optimizing the materials such as asphalt products,ultra-fine calcium carbonates and nano-plugging agents.The laboratory tests show that the performance parame-ters of the drilling fluids meet the operation requirements and the plugging performance is excellent.Specifically,the drilling fluid den-sity is 1.52-1.62 g/cm3;funnel viscosity,80-100 s;yield point,8-13 Pa;emulsion-breaking voltage,above 500 V;oil-water ratio,(80:20)to(85:15);API fluid loss,≤1.5 mL;HTHP fluid loss at 120℃,≤2 mL.The presented anti-collapse system of oil-based drilling fluids has been successfully applied to Jimsar shale oil horizontal wells with a long openhole wellbore.The average borehole en-largement rate of the openhole wellbore and the rate of downhole complex issues were 3.03％and 0.55％respectively.The anti-collapse system effectively ensured the drilling safety of the build-up and horizontal wellbores.
关键词
吉木萨尔/页岩油/长裸眼/油基钻井液/防塌技术Key words
Jimsar/shale oil/long openhole wellbore/oil-based drilling fluid/anti-collapse technology引用本文复制引用
出版年
2025
NETL
NSTL
万方数据