3D FEM随钻电磁波电阻率测井响应影响因素研究
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摘要
影响随钻电磁波电阻率测井仪器响应的因素主要来自两方面:一方面是自身结构因素,包含线圈、天线凹槽、盖板、钻铤等,这些因素通过影响接收线圈感应电动势的幅度,进而对电阻率测量结果产生影响;另一方面因素来自外界环境,包括井眼泥浆、围岩、侵入、介电常数以及地层各向异性等,测井过程中的仪器响应,是对井下多种不同介质的综合响应,为了达到探测原状地层电阻率的目的,需要扣除其它因素对仪器响应的影响。因而研究影响随钻电磁波电阻率测井响应的因素,对测井资料的解释与应用是十分必要的。本文以随钻电磁波电阻率仪器WPR(Wave Propagation Resistivity)为算例,建立真实的3维仪器结构,采用3维有限元3 D FEM(Three-Dimensional Finite Element Model)方法,针对真实仪器自身结构以及外界环境因素对仪器响应造成的影响进行了数值模拟,并利用解析解对本文的数值解进行了验证。感应电动势绝对值随着线圈半径、线圈凹槽宽度、天线槽长度、盖板占空比增大而明显增大;随着凹槽深度增加而减小。其中,浅探测模式受以上因素影响较深探测模式更大。此外,感应电动势绝对值受金属钻铤的电导率影响较小。在外界环境因素方面,井眼与泥浆存在使视幅度比电阻率偏小,视相位差电阻率偏大;泥浆电阻率越大,对仪器响应造成的影响越小;各向异性使视幅度比电阻率与视相位差电阻率均偏大;泥浆侵入、围岩、介电常数以及各向异性因素使视幅度比电阻率与视相位差电阻率在数值上差异逐渐增大;泥浆侵入使视相位差电阻率与视幅度比电阻率差异先增大再减小;介电常数影响在高阻地层中更加明显,其中视相位差电阻率受影响更大。
Both of the structure of logging tools and environmental factors affect the response of LWD(Logging While Drilling)electromagnetic wave resistivity tools. The structures of the receiver coil, coil groove, coil cover and metal mandrel impact on the amplitude of the induced voltage in the receiver coil, and the measurements of resistivity are affected indirectly. In terms of environment factors, the responses of borehole-mud, surrounding rock, drilling fluid invasion, dielectric properties and anisotropy contribute to the real response of logging tools. These responses corresponding to environment factors should be removed to obtain the real response of the undisturbed formation. Thus, it is indeed imperative to study the effects of tool-structure and environments factors for the interpretation and application of logging information. In this paper, an example of numerical simulation of a wave propagation resistivity tool based on a 3D FEM(Three-dimensional Finite Element Model)method is introduced. We have conducted the numerical simulation of the tool-structure and environments factors based on the real structure of the logging tools. The absolute value of the induced voltage rapidly increases with an increase of coil radius, width of coil groove, length of coil slot, and space proportion of cover. The absolute value decreases with an increase of the depth of the coil groove. The shallow mode is more susceptible than the deep mode to the above factors. Moreover, the absolute value has a weak relation with the conductivity of the metal drill collar. In the respect of environmental factors, the apparent amplitude ratio resistivity decreases while the apparent phase shift resistivity increases due to the borehole-mud while the effects of mud become weaker as the mud resistivity increases; both in the apparent amplitude ratio and the apparent phase shift resistivity increase due to the anisotropy. The value difference between the apparent amplitude ratio and apparent phase shift resistivity increases owing to the effects of the mud invasion, surrounding rock, dielectric or anisotropy. The difference of the two above resistivity values increases at first, and then decreases due to the effect of mud. The influence of dielectric properties becomes more significant in high resistivity formations. Apparent phase shift resistivity is more sensitive than the apparent amplitude ratio resistivity for dielectric effects.
Both of the structure of logging tools and environmental factors affect the response of LWD(Logging While Drilling)electromagnetic wave resistivity tools. The structures of the receiver coil, coil groove, coil cover and metal mandrel impact on the amplitude of the induced voltage in the receiver coil, and the measurements of resistivity are affected indirectly. In terms of environment factors, the responses of borehole-mud, surrounding rock, drilling fluid invasion, dielectric properties and anisotropy contribute to the real response of logging tools. These responses corresponding to environment factors should be removed to obtain the real response of the undisturbed formation. Thus, it is indeed imperative to study the effects of tool-structure and environments factors for the interpretation and application of logging information. In this paper, an example of numerical simulation of a wave propagation resistivity tool based on a 3D FEM(Three-dimensional Finite Element Model)method is introduced. We have conducted the numerical simulation of the tool-structure and environments factors based on the real structure of the logging tools. The absolute value of the induced voltage rapidly increases with an increase of coil radius, width of coil groove, length of coil slot, and space proportion of cover. The absolute value decreases with an increase of the depth of the coil groove. The shallow mode is more susceptible than the deep mode to the above factors. Moreover, the absolute value has a weak relation with the conductivity of the metal drill collar. In the respect of environmental factors, the apparent amplitude ratio resistivity decreases while the apparent phase shift resistivity increases due to the borehole-mud while the effects of mud become weaker as the mud resistivity increases; both in the apparent amplitude ratio and the apparent phase shift resistivity increase due to the anisotropy. The value difference between the apparent amplitude ratio and apparent phase shift resistivity increases owing to the effects of the mud invasion, surrounding rock, dielectric or anisotropy. The difference of the two above resistivity values increases at first, and then decreases due to the effect of mud. The influence of dielectric properties becomes more significant in high resistivity formations. Apparent phase shift resistivity is more sensitive than the apparent amplitude ratio resistivity for dielectric effects.
引文
[1]ANDERSON B,BARBER T,LLING M,et al.Observations of large dielectric effects on LWD propagation-resistivity logs[C].SPWLA48th Annual Logging Symposium,Austin,2007.
[2]DAVYDYCHEVA S,DRUSKIN V,HABASHY T.An efficient finite-difference scheme for electromagnetic logging in 3D anisotropic in homogeneous media[J].Geophysics,2003,68(5):1525-1536.
[3]DYATLOV G,ONEGOVA E,DASHEVSKY Y.Efficient 2.5D electromagnetic modeling using boundary integral equations[J].Geophysics,2015,80(3):E164-E173.
[4]LI J.Comparing tool eccentricity effects on LWD propagation resistivity for oil-based and waterbased muds[J].Seg Technical Program Expanded Abstracts,2008,27(1):3713.
[5]JACKSON C,HAGIWARA T.A new simultaneous anisotropy and dielectric correction algorithm for LWD resistivity measurements[C].SPWLA 39th Annual Logging Symposium,Houston,1998.
[6]MEYER W H.Analysis of environmental corrections for propagation resistivity tools[J].SPWLA 41th Annual Logging Symposium,Houston,2000.
[7]MICHAEL S.BITTAR,HU H Y,et al.The effects of rock anisotropy on LWD toroidal resistivity sensors[C].SPWLA 44th Annual Logging Symposium.Houston,2004.
[8]YANG J,OMERAGIC D,LIU C,et al.Bed-Boundary effect removal to aid formation resistivity interpretation from LWD propagation measurements at all dip angles[C].SPWLA 46th Annual Logging Symposium.New Orleans,2005.
[9]杨震,杨锦舟,韩来聚.随钻电磁波电阻率测井实时井眼影响校正[J].石油勘探与开发,2013,40(5):625-629.[YANG Z,YANG JZ,HAN L J.A real-time borehole correction of electromagnetic wave resistivity logging while drilling[J].Petroleum Exploration and Development,2013,40(5):625-629.]
[10]范宜仁,胡云云,李虎,等.随钻电磁波测井仪器偏心条件下响应模拟与分析[J].中国石油大学学报(自然科学版),2014,38(2):59-66.[FAN Y R,HU Y Y,LI H,et al.Numerical modeling and analysis of responses of eccentric electromagnetics logging while drilling tool[J].Journal of China University of Petroleum(Edition of Natural Science),2014,38(2):59-66.]
[11]宋殿光,段宝良,魏宝君,等.金属钻铤对随钻电磁波电阻率测井仪测量信号的影响[J].测井技术,2014,38(2):201-205.[SONG DG,DUAN B L,WEI B J.The Influence of metal mandrel on electromagnetic resistivity logging responses[J].Well Logging Technology,2014,38(2):201-205.]
[12]杨震,刘庆成,岳步江,等.随钻电磁波电阻率测井仪器响应影响因素数值模拟[J].测井技术,2011,35(4):325-330.[YANG Z,LIUQ C,YUE B J,et al.Numerical simulation on influence factors of electromagnetic wave resistivity logging while drilling response[J].Well Logging Technology,2011,35(4):325-330.]
[13]陈爱新.随钻电磁波测井环境影响分析[J].石油地球物理勘探,2006(5):601-605.[CHEN A X.Electromagnetic logging-while-drilling environmental impact analysis[J].Geophysical Prospecting For Petroleum,2006(5):601-605.]
[14]吴宝玉,夏宏泉,张智勇.随钻电阻率测井的围岩影响及校正方法研究[J].西南石油学院学报,2006,28(6):20-23+112-113.[WUB Y,XIA H Q,ZHANG Z Y.Effect of shoulder beds on resistivity logging while drilling and its correction method[J].Journal Of Southwest Petroleum Institute,2006,28(6):20-23+112-113.]
[15]刘红岐,夏宏泉,郭璞,等.随钻电阻率测井介电效应校正图版分析及方法[J].西南石油大学学报:自然科学版,2010,32(2):58-62+198.[LIU H Q,XIA H Q,GUO P,et al.Study on the correction chart for dielectric effect of resistivity logging while drilling[J].Journal Of Southwest Petroleum University(Science&Technology Edition),2010,32(2):58-62+198.]
[16]夏宏泉,刘之的,朱猛,等.随钻电阻率测井的环境影响校正主次因素分析[J].测井技术,2008,32(2):159-163.[XIA H Q,LIUZ D,ZHU M,et al.Analysis of the primary and secondary environmental effects correction on LWD resistivity log[J].Well Logging Technology,2008,32(2):159-163.]
[17]刘国胜,杨海东,汤健超.复杂地质层中电磁波测井响应特性的数值研究[J].中南大学学报:自然科学版,2013,44(2):656-661.[LIU G S,YANG H D,TANG J C.Numerical investigation for responses of electrical logging-while-drilling in complex formations[J].Journal of Central South University(Science and Technology),2013,44(2):656-661.]
[18]魏宝君,徐丹,王莎莎.通讯槽对电磁波传播随钻测量信号的影响[J].中国石油大学学报:自然科学版,2011,35(1):56-60.[WEI BJ,XU D,WANG S S.Influence of communication slots on signal of electromagnetic propagation measurement while drilling[J].Journal of China University of Petroleum(Edition of Natural Science),2011,35(1):56-60.]
[19]魏宝君,田坤,张旭,等.用并矢Green函数的矢量本征函数展开式评价偏心对随钻电磁波电阻率测井响应的影响[J].中国石油大学学报:自然科学版,2010,34(5):57-62.[WEI B J,TIAN K,ZHANG X,et al.Evaluating influence of eccentricity on response of electromagnetic wave resistivity logging-while-drilling by vector eigenfunction expansion formulae for dyadic Green’s functions[J].Journal of China University of Petroleum(Edition of Natural Science),2010,34(5):57-62.]
[20]文艺,韩晓梅.大斜度井随钻电磁波层厚影响模拟及机理分析[J].西南石油大学学报(自然科学版),2013,35(04):75-80.[WENY,HAN X M.Simulation of bed thickness effect and mechanism analysis of electromagnetic wave resistivity logging while drilling in highly-deviated wells.Journal Of Southwest Petroleum University(Science&Technology Edition),2013,35(04):75-80.]
[21]范宜仁,李炜,李虎,等.基于时域有限差分亚网格与共形网格技术的随钻电磁波测井响应数值模拟[J].测井技术,2015,39(5):561-566.[FAN Y R,LI W,LI H,et al.Numerical simulation of electromagnetic LWD response based on subgridding algorithm and conformal FDTD[J].Well Logging Technology,2015,39(2):561-566.]
[22]MEHDI.H,HENRI.B,BENOIT D,et al.Dielectric dispersion:A new wireline petrophysical measurement[C].SPE Annual techogic Conference.and Exhibition,Denver,21-24 September 2008.
[23]赵淑芳.高频场中岩石介电性质的实验研究[J].石油学报,1982(s1):63-72.[ZHAO S F.Study of dielectric properity of rocks in a high-frequency field[J].Acta Petrolei Sinica,1982(s1):63-72.]
[2]DAVYDYCHEVA S,DRUSKIN V,HABASHY T.An efficient finite-difference scheme for electromagnetic logging in 3D anisotropic in homogeneous media[J].Geophysics,2003,68(5):1525-1536.
[3]DYATLOV G,ONEGOVA E,DASHEVSKY Y.Efficient 2.5D electromagnetic modeling using boundary integral equations[J].Geophysics,2015,80(3):E164-E173.
[4]LI J.Comparing tool eccentricity effects on LWD propagation resistivity for oil-based and waterbased muds[J].Seg Technical Program Expanded Abstracts,2008,27(1):3713.
[5]JACKSON C,HAGIWARA T.A new simultaneous anisotropy and dielectric correction algorithm for LWD resistivity measurements[C].SPWLA 39th Annual Logging Symposium,Houston,1998.
[6]MEYER W H.Analysis of environmental corrections for propagation resistivity tools[J].SPWLA 41th Annual Logging Symposium,Houston,2000.
[7]MICHAEL S.BITTAR,HU H Y,et al.The effects of rock anisotropy on LWD toroidal resistivity sensors[C].SPWLA 44th Annual Logging Symposium.Houston,2004.
[8]YANG J,OMERAGIC D,LIU C,et al.Bed-Boundary effect removal to aid formation resistivity interpretation from LWD propagation measurements at all dip angles[C].SPWLA 46th Annual Logging Symposium.New Orleans,2005.
[9]杨震,杨锦舟,韩来聚.随钻电磁波电阻率测井实时井眼影响校正[J].石油勘探与开发,2013,40(5):625-629.[YANG Z,YANG JZ,HAN L J.A real-time borehole correction of electromagnetic wave resistivity logging while drilling[J].Petroleum Exploration and Development,2013,40(5):625-629.]
[10]范宜仁,胡云云,李虎,等.随钻电磁波测井仪器偏心条件下响应模拟与分析[J].中国石油大学学报(自然科学版),2014,38(2):59-66.[FAN Y R,HU Y Y,LI H,et al.Numerical modeling and analysis of responses of eccentric electromagnetics logging while drilling tool[J].Journal of China University of Petroleum(Edition of Natural Science),2014,38(2):59-66.]
[11]宋殿光,段宝良,魏宝君,等.金属钻铤对随钻电磁波电阻率测井仪测量信号的影响[J].测井技术,2014,38(2):201-205.[SONG DG,DUAN B L,WEI B J.The Influence of metal mandrel on electromagnetic resistivity logging responses[J].Well Logging Technology,2014,38(2):201-205.]
[12]杨震,刘庆成,岳步江,等.随钻电磁波电阻率测井仪器响应影响因素数值模拟[J].测井技术,2011,35(4):325-330.[YANG Z,LIUQ C,YUE B J,et al.Numerical simulation on influence factors of electromagnetic wave resistivity logging while drilling response[J].Well Logging Technology,2011,35(4):325-330.]
[13]陈爱新.随钻电磁波测井环境影响分析[J].石油地球物理勘探,2006(5):601-605.[CHEN A X.Electromagnetic logging-while-drilling environmental impact analysis[J].Geophysical Prospecting For Petroleum,2006(5):601-605.]
[14]吴宝玉,夏宏泉,张智勇.随钻电阻率测井的围岩影响及校正方法研究[J].西南石油学院学报,2006,28(6):20-23+112-113.[WUB Y,XIA H Q,ZHANG Z Y.Effect of shoulder beds on resistivity logging while drilling and its correction method[J].Journal Of Southwest Petroleum Institute,2006,28(6):20-23+112-113.]
[15]刘红岐,夏宏泉,郭璞,等.随钻电阻率测井介电效应校正图版分析及方法[J].西南石油大学学报:自然科学版,2010,32(2):58-62+198.[LIU H Q,XIA H Q,GUO P,et al.Study on the correction chart for dielectric effect of resistivity logging while drilling[J].Journal Of Southwest Petroleum University(Science&Technology Edition),2010,32(2):58-62+198.]
[16]夏宏泉,刘之的,朱猛,等.随钻电阻率测井的环境影响校正主次因素分析[J].测井技术,2008,32(2):159-163.[XIA H Q,LIUZ D,ZHU M,et al.Analysis of the primary and secondary environmental effects correction on LWD resistivity log[J].Well Logging Technology,2008,32(2):159-163.]
[17]刘国胜,杨海东,汤健超.复杂地质层中电磁波测井响应特性的数值研究[J].中南大学学报:自然科学版,2013,44(2):656-661.[LIU G S,YANG H D,TANG J C.Numerical investigation for responses of electrical logging-while-drilling in complex formations[J].Journal of Central South University(Science and Technology),2013,44(2):656-661.]
[18]魏宝君,徐丹,王莎莎.通讯槽对电磁波传播随钻测量信号的影响[J].中国石油大学学报:自然科学版,2011,35(1):56-60.[WEI BJ,XU D,WANG S S.Influence of communication slots on signal of electromagnetic propagation measurement while drilling[J].Journal of China University of Petroleum(Edition of Natural Science),2011,35(1):56-60.]
[19]魏宝君,田坤,张旭,等.用并矢Green函数的矢量本征函数展开式评价偏心对随钻电磁波电阻率测井响应的影响[J].中国石油大学学报:自然科学版,2010,34(5):57-62.[WEI B J,TIAN K,ZHANG X,et al.Evaluating influence of eccentricity on response of electromagnetic wave resistivity logging-while-drilling by vector eigenfunction expansion formulae for dyadic Green’s functions[J].Journal of China University of Petroleum(Edition of Natural Science),2010,34(5):57-62.]
[20]文艺,韩晓梅.大斜度井随钻电磁波层厚影响模拟及机理分析[J].西南石油大学学报(自然科学版),2013,35(04):75-80.[WENY,HAN X M.Simulation of bed thickness effect and mechanism analysis of electromagnetic wave resistivity logging while drilling in highly-deviated wells.Journal Of Southwest Petroleum University(Science&Technology Edition),2013,35(04):75-80.]
[21]范宜仁,李炜,李虎,等.基于时域有限差分亚网格与共形网格技术的随钻电磁波测井响应数值模拟[J].测井技术,2015,39(5):561-566.[FAN Y R,LI W,LI H,et al.Numerical simulation of electromagnetic LWD response based on subgridding algorithm and conformal FDTD[J].Well Logging Technology,2015,39(2):561-566.]
[22]MEHDI.H,HENRI.B,BENOIT D,et al.Dielectric dispersion:A new wireline petrophysical measurement[C].SPE Annual techogic Conference.and Exhibition,Denver,21-24 September 2008.
[23]赵淑芳.高频场中岩石介电性质的实验研究[J].石油学报,1982(s1):63-72.[ZHAO S F.Study of dielectric properity of rocks in a high-frequency field[J].Acta Petrolei Sinica,1982(s1):63-72.]