胡清富, 谢春来, 田玉栋, 王焕文, 甘建国, 林辉. 伊拉克库尔德A油田原油注氮欠平衡钻井技术[J]. 石油钻探技术, 2021, 49(2): 32-36. DOI: 10.11911/syztjs.2021002
引用本文: 胡清富, 谢春来, 田玉栋, 王焕文, 甘建国, 林辉. 伊拉克库尔德A油田原油注氮欠平衡钻井技术[J]. 石油钻探技术, 2021, 49(2): 32-36. DOI: 10.11911/syztjs.2021002
HU Qingfu, XIE Chunlai, TIAN Yudong, WANG Huanwen, GAN Jianguo, LIN Hui. Under-Balanced Drilling Technique Using Nitrogen Injection into Crude Oil in Oilfield A of Iraq Kurdistan[J]. Petroleum Drilling Techniques, 2021, 49(2): 32-36. DOI: 10.11911/syztjs.2021002
Citation: HU Qingfu, XIE Chunlai, TIAN Yudong, WANG Huanwen, GAN Jianguo, LIN Hui. Under-Balanced Drilling Technique Using Nitrogen Injection into Crude Oil in Oilfield A of Iraq Kurdistan[J]. Petroleum Drilling Techniques, 2021, 49(2): 32-36. DOI: 10.11911/syztjs.2021002

伊拉克库尔德A油田原油注氮欠平衡钻井技术

Under-Balanced Drilling Technique Using Nitrogen Injection into Crude Oil in Oilfield A of Iraq Kurdistan

  • 摘要: 伊拉克库尔德A油田主力产层Bekhme碳酸盐岩储层裂缝发育,经过多年开发,地层压力逐年降低,钻井过程中极易发生钻井液漏失,不但导致机械钻速低,而且造成储层污染而出现单井产量低、含水率高等问题。为此,研究应用了以原油为钻井液、环空注氮气的欠平衡钻井技术, 该技术改变了传统的充气方式,氮气由套管头侧出口注入井眼,从尾管悬挂器上部筛管进入环空,随井眼内钻井液直接返至井口,即氮气只参与钻井液的部分循环,通过降低上部井眼内钻井液液柱压力来降低井底钻井液液柱压力,实现欠平衡钻进,且不影响井下MWD的测量和传输。该技术在A油田现场应用6口井,均顺利钻至设计井深,未发生井漏、井涌和井眼失稳等井下复杂情况,且实现了边钻进边生产的目的,与应用常规钻井技术的油井相比,机械钻速明显提高,单井产量提高了1~3倍,取得了良好的提速提产效果。研究与应用表明,原油注氮欠平衡钻井技术能满足老油田低地层压力、窄安全密度窗口地层安全钻井的需求,可提高油藏采收率及勘探开发效益。

     

    Abstract: Fractures in the Bekhme carbonate reservoir, the main production layer of oilfield A in Iraqi Kurdistan, have caused a reduction in the formation pressure over the last few years. As a result, downhole failures such as drilling fluid loss and reservoir pollution are often encountered, which causes there to be a low rate of penetration (ROP), low levels of production, high water cut, etc. We studied a new under-balanced drilling technique of injecting nitrogen into the annulus with crude oil as the drilling fluid. Different from the traditional mode of gas charging, nitrogen was injected into the wellbore from the annulus and directly flow back to the wellhead along with drilling fluid in the wellbore. In this process, nitrogen only participated in partial circulation of drilling fluid, and the pressure of the drilling fluid column in the bottom hole was reduced after that in the upper wellborehole was lowered, thus realizing under-balanced drilling without affecting downhole measurement while drilling (MWD) and its message transmission. This technique has been successfully applied to 6 wells in the oilfield without any downhole failures such as lost circulation, well kicks and wellbore instability, enabling drilling while producing. Compared with conventional drilling techniques, the ROP is greatly improved and single-well production increases 1 to 3 times. Research and applications demonstrate that the under-balanced drilling technique of nitrogen injection into crude oil enables safe drilling in mature oilfields characterized by low formation pressure and narrow safe density window, and improves oil recovery and exploration.

     

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