滨里海地区巨厚盐膏层蠕动规律研究
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摘要
盐膏层钻井,特别是深井盐膏层钻井,是一个世界性的技术难题。由于盐膏层的蠕动变形,国内外许多深井未钻达目的层都提前完钻或钻穿盐膏层后事故完钻或套管挤毁,由此浪费了大量的人力和物力,造成了重大的经济损失。滨里海盆地蕴藏着极其丰富的油气资源,但该地区广泛存在巨厚盐膏层(几百至几千米不等),且埋藏深,给钻井工作带来极大的挑战,如何安全快速地钻穿巨厚盐膏层是实现该盆地油气勘探突破的首要问题。
解决盐膏层钻井问题的关键是准确地分析盐膏层的蠕变规律,从而为钻井液密度的确定、井身结构的确定和套管柱的设计等提供可靠的依据。本文研究分析了哈萨克斯坦滨里海盆地盐膏层的分布规律,收集了该盆地钻井过程中的盐样及盐芯,利用X光衍射和扫描电镜方法分析了盐膏层的理化性能,利用声发射技术分析了盐岩的内部变形机制,利用三轴应力测试系统进行了盐芯的蠕变试验,分析了盐膏层的蠕动特性,建立了滨里海盆地巨厚盐膏层的蠕动模型。通过对实钻井使用的钻井液密度进行分析,认为控制井壁围岩的八面体剪应力,使得盐岩不发生损伤扩容,即可以保证安全钻井,从而提出了设计钻井液密度的八面体剪应力法,即给定盐岩井壁八面体剪应力处于扩容损伤边界值,通过公式计算得出保证井壁稳定的安全钻井液密度。通过三轴应力试验确定了盐岩的损伤扩容边界值,为3口井设计了钻进盐层的钻井液密度,通过和实钻应用的钻井液密度进行对比,利用该方法设计的钻井液密度完全可以满足安全钻井的需要,从而为中国石化勘探滨里海盆地盐下油气藏提供了技术支持。
Salt drilling, in deep wells particularly, is a big challenge to the world. Due to the creep of the salt, lots of deep wells were finished before target zone or accidently finished or casing collapse, leading to great economic loss. Pre-Caspian Basin is very rich in oil and gas, but thick layer of salt widespread in the region (ranging from several hundred to several kilometers), which is a big challenge to drilling. Therefore, the priority of oil and gas exploration in the basin is how to drill through the salt safely and fast. The key to solve the drilling problem is to properly analyse the creep law of the salt, which is the necessary basis for drilling fluid density design, well stucture design and casing design. Salt sample and core were gathered from Kazakhstan Pre-Caspian Basin, and after analysing physical, chemical and creep property experimentally, the creep model for the super thick salt at Pre-Caspian basin were established, and also, the drilling fluid density design method for drilling salt in this area was presented. Drilling practice of three wells proved that the density from this method could ensure safety drilling. And so this design method provides a reliable technical support for the oil and gas exploration beneath salt at Pre-Caspian Basin.
解决盐膏层钻井问题的关键是准确地分析盐膏层的蠕变规律,从而为钻井液密度的确定、井身结构的确定和套管柱的设计等提供可靠的依据。本文研究分析了哈萨克斯坦滨里海盆地盐膏层的分布规律,收集了该盆地钻井过程中的盐样及盐芯,利用X光衍射和扫描电镜方法分析了盐膏层的理化性能,利用声发射技术分析了盐岩的内部变形机制,利用三轴应力测试系统进行了盐芯的蠕变试验,分析了盐膏层的蠕动特性,建立了滨里海盆地巨厚盐膏层的蠕动模型。通过对实钻井使用的钻井液密度进行分析,认为控制井壁围岩的八面体剪应力,使得盐岩不发生损伤扩容,即可以保证安全钻井,从而提出了设计钻井液密度的八面体剪应力法,即给定盐岩井壁八面体剪应力处于扩容损伤边界值,通过公式计算得出保证井壁稳定的安全钻井液密度。通过三轴应力试验确定了盐岩的损伤扩容边界值,为3口井设计了钻进盐层的钻井液密度,通过和实钻应用的钻井液密度进行对比,利用该方法设计的钻井液密度完全可以满足安全钻井的需要,从而为中国石化勘探滨里海盆地盐下油气藏提供了技术支持。
Salt drilling, in deep wells particularly, is a big challenge to the world. Due to the creep of the salt, lots of deep wells were finished before target zone or accidently finished or casing collapse, leading to great economic loss. Pre-Caspian Basin is very rich in oil and gas, but thick layer of salt widespread in the region (ranging from several hundred to several kilometers), which is a big challenge to drilling. Therefore, the priority of oil and gas exploration in the basin is how to drill through the salt safely and fast. The key to solve the drilling problem is to properly analyse the creep law of the salt, which is the necessary basis for drilling fluid density design, well stucture design and casing design. Salt sample and core were gathered from Kazakhstan Pre-Caspian Basin, and after analysing physical, chemical and creep property experimentally, the creep model for the super thick salt at Pre-Caspian basin were established, and also, the drilling fluid density design method for drilling salt in this area was presented. Drilling practice of three wells proved that the density from this method could ensure safety drilling. And so this design method provides a reliable technical support for the oil and gas exploration beneath salt at Pre-Caspian Basin.
引文
[1]唐继平,王书琪,陈勉.盐层钻井理论与实践[M].北京:石油工业出版社,2004:15-42
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[3]曾义金,王文立,石秉忠.深层盐膏层蠕变特性研究及其在钻井中的应用[J].石油钻探技术,2005,33(5):48-51
[4]曾义金.深部盐膏层蠕变关系研究[J].石油钻探技术,2004,32(3):5-7
[5]张锦荣,陈安明,周玉苍.塔里木深井盐膏层钻井技术[J].石油钻探技术,2003,31(6):25-26
[2]张传进.岩石力学三轴应力测试系统及应用[J].石油钻探技术,1995,12(4):3-6
[3]曾义金,王文立,石秉忠.深层盐膏层蠕变特性研究及其在钻井中的应用[J].石油钻探技术,2005,33(5):48-51
[4]曾义金.深部盐膏层蠕变关系研究[J].石油钻探技术,2004,32(3):5-7
[5]张锦荣,陈安明,周玉苍.塔里木深井盐膏层钻井技术[J].石油钻探技术,2003,31(6):25-26