測井資料與應用

(3)

2.5聲波測井

(AcousticLog)2.5.1測量原理

*聲波發生器激發聲波*聲波沿井壁滑行傳播*兩個接收探頭記錄聲波全波列信號*測量聲波傳播經過兩個接收探頭所用的時間△t

FullwaveformConventionalacousticlogrecordP(compressional),S(shear)andstoneleywaveformcompressional常規聲波測井一般提供聲波時差ΔtGRΔt不同的地層具有不同的聲波速度和時差Δt

2.5.3聲波孔隙度通常地層巖石骨架的聲速都遠大于孔隙中流體的聲速高孔隙地層飽含更多的流體,其聲速將較低

*記錄的總

t=骨架

t

+孔隙流體

t*聲波速度(或Δt)與孔隙度緊密相關soundsound2.5.4應用計算孔隙度估算地層破裂壓力地層出砂分析計算滲透率縱合密度測井資料制作合成地震剖面

Wyllie平均時間公式(WTA)

最常用的孔隙度公式

:

?s=

式中,△tma

純地層骨架的聲波時差;

△tf

孔隙流體的聲波時差;Cp

壓實校正系數.

Cp(△tf

△tma

)

(△tc

△tma

)壓實校正固結不好(欠壓實)的砂巖

Δt較高,用其計算的孔隙度偏高(≈28-50%),通常需進行壓實校正壓實校正公式:

致密地層Cp=1固結不好(欠壓實)地層

壓實系數Cp≈0.8–1.3壓實校正圖版

范例

砂巖Δt=110μs/ft

不校正:

Φ=40%

選擇Cp=1.5:

Φ

≈27%

泥質影響校正固結好(壓實)紗巖:固結差(非壓實)紗巖:簡單公式:

油,氣影響校正

油,氣的

t大于水---油/氣層處理出的

ΦAC

偏大油,氣影響校正系數:

氣層

Φt=0.7×ΦAC

油層

Φt=0.9×ΦAC

GRCleansandcleansand:

Δtlog

≈125μs/ft

Δtm≈55.5μs/ft

Δtf≈189μs/ftCp=1.2Vsh≈0.1(10%)

Φ

≈(125-55.5)/(189-55.50)/1.2–Vsh

≈69.5/133.5/1.2–0.1

≈0.43-0.1

≈0.33(%)Usecrossplot:Φ

≈0.3%

Φ

calculation

UsingacousticdataalongΔtΦ研究巖石的物理特性*可用AC資料計算出許多巖石的彈性摸量參數*著些彈性摸量參數可用來評價儲層壓裂,出砂等問題BoreholeBreakoutGoodBorehole井壁穩定性分析地層出砂分析

SandingPotentialPrediction用斯通利波計算滲透率*Permeabilityisaimportantparameterforreservoirevaluation*Permeabilityisdifficulttocalculatedaccurately*Stoneleywavecanbeusedtocalculatepermeabilitymoreaccurately

合成地震剖面2.6電阻率測井AMN0測量間距電源電壓表B測井儀器電場電阻率測井示意圖不同地層的電阻率

松軟地層(泥質砂巖)0.5ohmm-50ohmm.致密地層(碳酸巖)10ohmmto1000ohmm.

噴發巖(硬石膏)可高達幾千到上萬ohmmPresentationLinearscalelogarithmicscaleSandscale:0.02-200Limestonescale:2-20002.6.3DualLateralResistivityToolInvestigatedepth--deeplogRD80in--shallowlogRS60inUsedtocalculatetrueformationRt&SW

ReceiverGroundloopTransmitter2.6.4InductionToolSchematicConductivitylogInvestigatedepth--deeplogRD60in--shallowlogRS40inUsedtocalculatetrueformationRt&SW

*8Rtcurveswithdifferentinvestigationdepth(10–120in)*Theloggingcurvesseparateinthepermeablezone.*Theinvasionprofileshowsustheflushedzone,transitionzoneandvirginzone.HDIL

(highresolutiondigitalinductionlog)Usefocusedcurrent

*Veryshallow

investigation(2-12in)

*MeasureRtof

flushedzone(RXO)

*Usedforevaluation

ofinvadedaffection

2.6.5聚焦及微電阻率測井

2.6.6環境影響InvadedzoneNoneinvadedzone

泥漿侵入對地層的污染在泥漿侵入條件下的測井響應

主要的環境影響

●井眼垮塌●電阻率差異大的圍巖

●泥漿侵入.TheaffectionofbedthicknessLogpg7-4,fig7-5LowerRtofsurroundingbedHighRtofsurroundingbedBedthickness

Correction(Inductionlog)Bedthickness>6ftNocorrectionThinnerbedsneedmorecorrectionDifferentRsneeddifferentcorrectionChartforboreholecorrectiontoduallateral

Example

give:

Rm=1?m

RD=10?m

borehole=11in

RLLDcorr

≈10×1.4

≈14(?m)

Waterzone

Saltymud(Rm<Rw,lowRt

invaded):

Ra>Rxo>Rm

Freshwatermud(Rm>Rw,

highRtinvaded):

Ra<Rxo<Rm

Oilzone

Saltymud(Rm<Rw,lowRt

invaded):

Ra>Rxo>Rm

Freshwatermud(Rm>Rw,

highRtinvaded):

Ra>Rxo>Rm

Ra–apparentlogresistivity

Rxo–flushedzoneresistivity

Rm–mudresistivity

InvasionaffectionLowresistivityinvadedHighresistivityinvadedHighresistivityinvasion

Rw=0.04?m/29?CRmf=1.16?m/28.5?CRt(shallower)>Rt(deeper).Lowresistivityinvasion

Rw=1.14?m/30?CRmf=0.16?m/27.8?C