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华北油田廊固凹陷河西务潜山构造带杨税务潜山圈闭的奥陶系潜山储层是典型的破碎性储层[1],是目前渤海湾盆地最深、温度最高、最复杂的碳酸盐岩潜山油气藏。第1口潜山探井AT1井酸压后试油日产气41 万m3,日产油71 m3。AT2、AT3井均获高产工业油气流,进一步展示了该区块规模资源前景。但是该区块地层岩性变化剧烈,储层深埋5 200 m以上,温度超过180 ℃,在前期施工过程遇到井喷(超出钻台1~8 m)、气侵点火(10~15 m)、井漏、卡钻等复杂工况[2],同时,钻进过程中存在托压、机械钻速低、钻井液高温失效及随钻测量仪器故障率高等难题,严重制约了钻井时效。为此,在分析已完井钻井难点的基础上,结合区块地层岩性特点,通过优化钻井设计、优选钻具组合、设计抗高温钻井液等措施,形成安全、快、优钻井技术,为该地区及同类型井安全、提速施工提供借鉴。
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该区块自上而下钻遇主要地层及岩性为:平原组(0~400 m),黄土、流沙为主;东营组(400~1 600 m),砂泥岩互交、含砾砂岩;沙一—沙四段(1 600~4 400 m),砂泥岩互交、玄武岩、膏泥岩、火成岩及砾岩;石炭系—奥陶系(4 400~6 500 m),白云岩、灰质白云岩为主。前期常用井身结构见图1。图1(a)的井身结构裸眼段长达3 500 m以上,1 600~2 950 m为低压层,下部地层为高压层,钻井液难以维护,形成上漏下塌的复杂工况。钻遇下部地层时,提高钻井液密度,对上部地层钻柱造成压差托压现象,添加水力振荡器仍然托压350~400 kN,单次滑动钻进时间不能超过5 min,否则就会卡钻,调整轨迹所需进尺是正常情况的2~3倍。图1(b)采用尾管回接,增加了套管层序,5段制井眼轨道,造斜点3 500 m在玄武岩、泥膏岩层,调整井眼轨迹困难。图1(c)中4 610~6 174 m小井眼深部定向,钻遇高研磨、可钻性差地层,同时随钻测量仪器、螺杆及钻井液均受高温影响。图1(d)浅层大井眼定向,造斜率低,后期稳斜段钻遇玄武岩、煤层等复杂层位容易造成井壁垮塌、卡钻等复杂工况。
井身结构最终优化方案如图1(e)所示,采用四开井身结构,一开封固平原组上部流沙层,安装井口悬挂套管,确保井下安全;二开封固低压层,防止出现“上漏下塌”、卡钻等复杂工况,同时解决压差托压问题;三开封固岩性复杂地层,尾管坐进潜山地层,为低密度揭开潜山打基础;四开潜山储层专打专封。采用三段制轨道,轨迹控制井段选在3 100~3 400 m砂泥岩互层。
优化后的井身结构简化了套管层序,缩短裸眼段长度,简化井眼轨道,有效缓解了拖压现象。将提速难点段优化为自然降斜段,在进入超高温地层及入山前完成轨迹调整,为提速工具应用创造条件,同时避免了随钻测量工具、螺杆在超高温井段作业,降低了钻井液在超高温条件下因井眼轨迹调整具备润滑性的要求。优化后的钻井时效对比见表1。
表 1 钻井时效对比
Table 1. Comparison of drilling time efficiency
井型 完钻周期/d 造斜点
井深/m完钻井深/m 平均机械钻速/
(m · h−1)钻头使
用数量a 182 1600 5697 3.75 22 b 167 3500 5673 5.05 24 c 183 4610 6174 7.17 21 d 171 1500 6024 6.99 24 e 133 3200 6445 7.60 16 -
(1) PDC+孕镶齿设计。单独的PDC钻头剪切性好,但在高研磨、可钻性差的地层使用寿命短,见图2(a);单独的孕镶钻头抗研磨性好,但机械钻速慢,需要配合涡轮钻具使用,受限条件多,见图2(b)。因此,将PDC钻头的剪切性与孕镶钻头的抗研磨性相结合(图2(c)),在主切削齿中,有计划地摆放一些短基座切削齿,然后将孕镶齿暴露在外(图2(d)),当主切削齿损坏之后孕镶齿仍然可以继续钻进(图2(e))。
(2)专用定向PDC钻头优选。采用微螺旋浅内锥减震节5刀翼设计,提高工具面稳定性。超短保径,有效提高侧向力,缩短滑动进尺。优选高抗冲击T系列复合片高密度布齿,提高钻头抗冲击能力,增强钻头使用寿命。
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根据岩性特点与井眼轨道设计,对井底钻具组合与钻井参数进行优化。上直段采用0.75°螺杆+PDC(直5刀翼单排19 mm齿),以大排量、高转速极限钻进为主;造斜段采用水力振荡器+1.25°单弯螺杆+定向PDC(螺旋5刀翼双排13 mm齿),以缓解托压、提高造斜率为主;稳斜段采用1°单弯螺杆(等径双稳定器)+PDC(螺旋6刀翼双排16 mm齿)或扭力冲击器+PDC(螺旋6刀翼全双排13 mm齿),通过控制钻压或辅助破岩工具提高机械钻速;超高温井段采用常规钻柱+多维冲击器+孕镶齿PDC,将随钻测量、螺杆去除,减小故障率,最大程度提高机械钻速。在Ø152.4 mm井眼,采用Ø101.6 mm+ Ø127 mm复合钻杆,提高扭矩与钻压传递效率。
优化后在奥陶系井段(5 000~6 500 m)使用孕镶齿PDC钻头较之前平均机械钻速提高1~2倍,最高机械钻速3.82 m/h,单次入井进尺674 m,入井之后钻头损伤见图2(e)。
稳斜段钻进,在井段4 158~4 291 m使用扭力冲击器较使用螺杆的机械钻速高1~2倍,在井段4 291~4 444 m使用螺杆的机械钻速高于扭力冲击器。但上述井段与螺杆配合的PDC在出井之后磨损严重,表明在砾岩或玄武岩地层中使用扭力冲击器能很好保护切削齿,见图3。
图 3 扭力冲击器+PDC与螺杆+PDC入井后对比
Figure 3. Comparison between torque impactor + PDC and screw rod + PDC after running into the hole
在AT4井4 098~4 480 m井段使用上述2种不同的工具,机械钻速与AT1井接近且出井之后的钻头磨损程度也相近。为满足井眼轨迹调整的需求,在A101井采用螺杆+扭冲+全双排齿PDC效果显著,但螺杆强度不够(轴断);再次优化后采用水力振荡器+螺杆+全双排齿PDC组合,可以有效缓解托压、钻头过早失效等问题。
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钻井液在高温条件下应具备良好的携岩性、润滑性等特点以减少井底复杂工况。因此,对国内外钻井液抗高温降滤失剂(Driscal-D、SO-1、SMPC-Ⅲ、SMP-3、SMP-Ⅲ)、流型调节剂(HE300、HB-1、HB-2)、膨润土等材料的抗高温流变性进行实验,并采用OFI高温高压流变仪进行井底情况模拟测试,结果表明:膨润土含量为4%时,在220 ℃、16 h后出现增稠现象;使用SMP-3、SMP-Ⅲ体系220 ℃、16 h优于SMPC-Ⅲ体系,不会出现碳化结块现象。最终优化配方为3%膨润土+0.2%NaOH+0.3%抗高温增黏降滤失剂DriscalD+0.3%腈硅聚合物降滤失剂SO-1+2%磺化酚醛树脂SMP-3+2%磺化沥青Soletx+1.5%提切剂HB-2+石灰石。
随着温度升高,对钻井液采用阶梯式维护模式。以胶液的形式添加SMP-3、Soletx、HB-2、SO-1、Driscal D及乳化沥青等材料。同时,最大限度地使用固控设备,降低钻井液劣质固相含量,改善滤饼质量,使滤饼厚度不大于1 mm,并从严控制钻井液滤失量,尤其是高温高压滤失,保证钻井液在高温条件下的稳定性[9]。
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随钻测量脉冲发生器油囊(橡胶材料)是核心部件之一,但在高温高压下油囊易产生鼓胀或破裂,导致随钻测量仪器信号中断。因此,将橡胶油囊结构设计为全金属结构,可抗200 ℃以上高温。在AT6井循环温度175 ℃累计使用200 h工作稳定,但超过175 ℃仪器整体稳定性降低。
采取优化措施后,全井平均机械钻速从前期1.15 m/h提高至8 m/h以上,钻井周期从371 d(WX井)缩短至108 d(AT501井),平均钻井周期较前期已完井周期缩短50%。同时,采用简易控压技术防止井喷、气漏等事故,在某AX井气侵点火15次降低了井控风险。对煤层、炭质泥岩井段采取“进一退二、少打多划、稠浆裹带”等措施确保井下安全。
Optimized, safe and fast drilling technologies used in the ultra deep and high temperature wells in Yangshuiwu buried hill
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摘要: 为解决冀中地区廊固凹陷潜山构造带超深超高温潜山油气井在钻进过程中遇到漏、喷、卡、机械钻速低及轨迹控制困难等问题,在分析已完井钻井难点,调研国内超深井钻井提速技术基础上,采取了优化井身结构,简化井眼轨道,针对地层特点设计孕镶齿PDC钻头并优选钻具组合及钻井参数,研制220 ℃低固相抗高温钻井液,研发200 ℃全金属随钻测量井下脉冲发生器等措施。现场应用结果表明:优化后的井身结构与井眼轨道更易于井眼轨迹调整,使用高效PDC钻头与辅助提速、破岩工具相配合,平均机械钻速较之前提高了1~2倍,低固相抗高温钻井液在200 ℃性能稳定,满足安全施工需求,随钻测量全金属脉冲发生器在井温175 ℃条件下可持续工作超过200 h。该区块平均钻井周期较前期完井缩短了50%,最深完钻井深6 455 m、实测井底静止温度207 ℃。所采取的安全、优、快钻井技术可对后期超深、超高温井钻井提供借鉴与参考。Abstract: In the drilling process of oil and gas wells in the ultra deep and ultra high temperature buried hill of buried-hill structural belt in Langgu sag of central Hebei, several problems are encountered, including leakage, blowout, sticking, low rate of penetration (ROP) and difficult trajectory control. In order to solve these problems, this paper firstly analyzed the drilling difficulties of drilled wells and investigated domestic ROP improvement technologies of ultra deep wells. Then, a series of measures were taken. For example, the casing program was optimized and the well track was simplified. Based on the stratigraphic characteristics, impregnated-tooth PDC bit was designed, and bottom hole assembly (BHA) and drilling parameters were optimized. In addition, low solid and high temperature (220 ℃) drilling fluid was prepared, and 200 ℃ all-metal downhole pulser for measurement while drilling was developed. The field application results show that the optimized casing program and well track are convenient for the adjustment of wellbore trajectory. Owing to the application of efficient PDC bit, combined with the supporting ROP improvement and rock breaking tools, the average ROP is increased by 1-2 times. The performance of low solid and high temperature drilling fluid is stable under the temperature of 200 ℃, which can meet the requirements of safe construction. The all-metal downhole pulser for measurement while drilling can work continuously for over 200 h under the well temperature of 175 ℃. The average drilling cycle is 50% shorter than that in the early stage, the maximum total well depth is 6 455 m and the measured bottom hole static temperature is 207 ℃ in this block. In conclusion, the optimized, safe and fast drilling technologies adopted here can provide references for the drilling of ultra deep and ultra high temperature wells in the late stage.
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Key words:
- deep layer /
- buried hill /
- casing program /
- trajectory control /
- drilling fluid /
- high temperature /
- ROP improvement /
- measurement while drilling
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表 1 钻井时效对比
Table 1. Comparison of drilling time efficiency
井型 完钻周期/d 造斜点
井深/m完钻井深/m 平均机械钻速/
(m · h−1)钻头使
用数量a 182 1600 5697 3.75 22 b 167 3500 5673 5.05 24 c 183 4610 6174 7.17 21 d 171 1500 6024 6.99 24 e 133 3200 6445 7.60 16 -
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