11. Dasar Analisa Log Kwantitatif

WELL LOGGING ANALYSIS. WELL LOGGING ANALYSIS. 11.Basic Log Analysis.11.Basic Log Analysis.

MustotoMustoto MoehadiMoehadi..HP. 085814457579HP. 085814457579

[email protected]

5MT – Oil & Gas Business Series.

MM - Petroleum Geology and Explorations.

Basic Log Analysis

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Checking Checking KwalitasKwalitas Log.Log.

By Ir. Mustoto Moehadi. MM


Basic Log Analysis

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GeneralGeneralCheck the Log Header, Well data, Parameters, Tools / Services run, Calibrations, Mud data

Compare Main Log and Repeat Section

Look for known features

Find any suspicious trends


Basic Log Analysis

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DepthDepthMake sure all curves on the Log are ON-Depth

Check the remarks section to see how the depth was tied in

Make sure all logs recorded in that Job are On-Depth

Check T.D and Casing depth (Driller vsLogger)


Basic Log Analysis

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TensionTensionLook for Tension pickup if Tool had hit the well bottom

Look for sections or zones where there is sudden increase or decrease in Tension and corroborate with Caliper Log


Basic Log Analysis

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CaliperCaliperDetermine the type of Caliper used

Check Casing ID

Check for mud cake formation against known permeable zones

Define and differentiate between big hole and washout

See if caliper readings are within expected values

Check the BHV and AHV computations


Basic Log Analysis

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Gamma rayGamma rayExpect to have High GR against Shalesand Low GR against reservoir rocks

Check for hole size effect, mud weight effect, tool position effect

If CSNG is run then see if the K, U, T concentrations on the log are within expected values for the Shale minerals


Basic Log Analysis

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Spontaneous PotentialSpontaneous PotentialCheck whether SP curve is on depth and correlates with GR

Check for Noise or wavy character

Check if the Shale baseline is between the 7th and 9th division of Track1

Normal baseline drift is expected

Depending on Mud used, check the SP signal against thick, clean, water bearing porous sands


Basic Log Analysis

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ResistivityResistivityResistivity curves can vary over a very wide range

Check if the correct Tool was used for the given Mud conditions

Based on the mud check for correct Invasion profile

In non porous rocks like anhydrite or salt resistivity's can be very high

In homogenous Shale's all 3 curves must overlay and read low values

Pad type Tools like MSFL might show spiky but the Deep and Medium / Shallow should be smoother

What might happen in formations with high Dip angles?MM - Petroleum Geology and Explorations.

Basic Log Analysis

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DensityDensityCheck the scales (RHOB or DPHI)

If DPHI is plotted then check for Matrix selection

If RHOB is plotted then are the scales Limestone compatible?

Look for close to zero Density Correction in front of gauged hole

Unless Barites in mud or Coals in formation are present, the Density correction should be mostly positive

Density readings are sensitive to Pad contact and therefore repeatability cannot be guaranteedCheck Calibration


Basic Log Analysis

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NeutronNeutronGenerally smoother than Density curve

Check for correct value in known Shale zones

In clean water bearing matrix rock, Neutron should overlay Density


Basic Log Analysis

12Typical Neutron Typical Neutron –– Density.Density.


Basic Log Analysis

13Typical Density Typical Density -- NeutronNeutron

PE PE


Basic Log Analysis

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SonicSonicCheck for Cycle Skipping or Noise

Check for DT against Shale

Check for DT against Clean water bearing Matrix rocks

Always have the Caliper log available for LQA

Check for DT inside Casing. It should be 57 µsec/ft


Basic Log Analysis

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MenghitungMenghitung TemperaturTemperatur dandanResistivity.Resistivity.



Basic Log Analysis

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Archie EquationArchie Equation

nT

mw

R*R*aSw

φ=

Sw decimal Water SaturationRw Ω-m Formation Water ResistivityΦ decimal PorosityRT Ω-m True Resistivity (ohms-m)a Tortuosity Factorm Cementation Factorn Saturation Exponent


Basic Log Analysis

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Archie EquationArchie Equation

nT

mw

R*R*aSw

φ=

Porosity > 16% Porosity < 16%(Humble) (Tixier)

a 1 0.62 0.81m 2 2.15 2n 2 2 2

SANDSTONESCARBONATES

TemperatureTemperatureSurface

Temperature(ST)

Bottom Hole Temperature

(BHT)

Bottom Hole Static Temperature

(BHST)

ST

BHT

TemperatureTemperature

Tf : Formation TemperatureBHT : Bottom Hole Temperature (from log)Tms : Mean Surface TemperatureTD : Total Depth (logger)D : Depth

(valid for vertical wells)

msms

f TD*TD

TBHTT +⎟⎠⎞

⎜⎝⎛ −

=

Tms (average annual temperature of a region)


Basic Log Analysis

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Y = Bottom hole temperatur (BHT) = 250oF.X = Total Depth (TD) = 15,000 ft.C = Surface temperatur = 70oF.

Cara menghitung m adalah:

y – c 250o – 70om = == > m =

x 15,000 ft

m = temperatur gradient = 0.012o/ft or 1,2o/100 ft.

MenghitungMenghitung Gradient Gradient TemperaturTemperatur..


Basic Log Analysis

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ESTIMASI T TEMPERATUR FORMASI.Suhu di permukaan pada lokasi dapat diukur.

Suhu didasar lubang bor diukur dengan thermometer maximum.

Untuk mengukur suhu pada kedalaman tertentu antaradasar lubang bor dengan permukaan dapat menggunakanchart atau dengan perhitungan.

EstimasiEstimasi TemperaturTemperatur FormasiFormasi....


Basic Log Analysis

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Menhitung Temperatur Formasi.

m = temperatur gradient = 0.012o/ft or 1,2o/100 ft..X = Formation depth = 8,000 ft.C = Surface temperatur = 70oF.

Cara menghitung Y (temperatur formasi) adalah:

Y = (m) * (x) * (c).

Y = (0.012) * (8000) * (70) = 166oF.

MenghitungMenghitung TemperaturTemperatur FormasiFormasi..


Basic Log Analysis

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MenghitungMenghitung TemperaturTemperatur FormasiFormasi

Menhitung Temperatur Formasi.


Basic Log Analysis

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8.Temperature8.Temperature


Basic Log Analysis

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8.Temperature8.Temperature Mean Surface Temperature

If Tms unknown, then assume 75°F/ 24°C

LatihanLatihan PerhitunganPerhitungan TemperaturTemperaturFind Formation Temperature in ˚F at following depths

(assume depths are true vertical depths)Temperature Assumption: Tms=70˚F

10001000’’ Temp =Temp =20002000’’ Temp =Temp =29152915’’ Temp = Temp = 29702970’’ Temp =Temp =31453145’’ Temp =Temp =34203420’’ Temp =Temp =35003500’’ Temp =Temp =

10 minutesMM - Petroleum Geology and Explorations.

Basic Log Analysis

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MENENTUKAN RESISTIVITAS FLUIDA PADA SUHU YANG BERBEDA serta MENENTUKAN KONSENTRASI LARUTAN GARAM NaCl.Rmf, Rm dan Rmc diukur dipermukaan.

Suhu dipermukaan dapat diketahui.

Suhu didasar lubang bor dapat diketahui.

Sehingga suhu pada kedalaman tertentu dapat dicari.

Chart Gen-9 untuk mencari harga Rmf, Rm dan Rmcpada kedalaman tertentu, serta bisa dipakai untukmencari konsentrasi larutan NaCl.

MenentukanMenentukan ResistivitasResistivitas..


Basic Log Analysis

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EstimasiEstimasi RmfRmf dandan RmcRmc

Estimation of Rmf and Rmc


Basic Log Analysis

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9. 9. EstimasiEstimasi RmfRmf dandan RmcRmc


Basic Log Analysis

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9. 9. EstimasiEstimasi RmfRmf dandan RmcRmc RRww and Temperatureand Temperature

( )( )kT

kT*RRf

wwwf

++

=

Rwf : Rw corrected for TemperatureRw : Rw at known reference temperature TwTw : Known reference temperaturek : temperature constant

6.77 (temperature expressed in °F)21.5 (temperature expressed in °C)

Using previous Temperature calculations, find Rwin ohm-meters at following depths and ˚F

Rw = 0.08 ohm-meters at 80 F

10001000’’ Temp =Temp =20002000’’ Temp =Temp =29152915’’ Temp = Temp = 29702970’’ Temp =Temp =31453145’’ Temp =Temp =34203420’’ Temp =Temp =35003500’’ Temp =Temp =

10 minutes

89.8

127.6128.7132.1137.5139.1

109.5Rw=Rw=Rw=Rw=Rw=Rw=Rw=

JawabanJawaban PerhitunganPerhitungan RwRw


Basic Log Analysis

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AnalisaAnalisa KwalitatifKwalitatifQuick Look Analysis ProcessQuick Look Analysis Process



Basic Log Analysis

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Quick Look Analysis ProcessQuick Look Analysis Process1. Perform Log Quality Control2. Zoning - Clean Reservoir & Shale (GR &

SP)3. Permeability Indicator (Resistivity)4. Lithology5. Formation Water Resistivity (Rw)6. Select Analysis depths7. Gather Porosity and Resistivity8. Water Saturation using Archie Equation.9. Evaluate zones with Sw < 50%


Basic Log Analysis

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Example # 1Example # 1LatihanLatihan Baca Baca PetaPeta..



Basic Log Analysis

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CobalahCobalah membacamembaca Log Log iniini !!!!!!!!PE XPLOT

PORO

5704

5725

5667

5609

DEPTH SwDensity Porosit

y

Neutron Porosit

y

Deep IndCALIGR

(DIL)

Quick Look Log Example # 4 (45 minutes)Quick Look Log Example # 4 (45 minutes)use use RwRw =0.04=0.04 Ω-m @ BHT


Basic Log Analysis

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Example # 2Example # 2



Basic Log Analysis

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PE XPLOT PORO

1600-1606

1656-1672

1576-1590

1530-1538

DEPTH SwDensity Porosity

Neutron PorosityDeep IndCALIGR-

(SDL)

Quick Look (30 minutes)Quick Look (30 minutes)use use RwRw =0.04=0.04 Ω-m @ BHT


Basic Log Analysis

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Example # 3Example # 3



Basic Log Analysis

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Basic Log Analysis

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EXAMPLE # 3

PE XPLOT PORO

8098-8105

8105-8112

8095-8097

8029-8048

DEPTH SwDensity Porosity

Neutron PorosityDeep IndCALIGR (DIL)

Quick Look (45 minutes) Quick Look (45 minutes) use use RwRw =0.04=0.04 Ω-m @ BHT


Basic Log Analysis

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Find the Pay Zone Find the Pay Zone Example 4 Example 4 !!use use RwRw =0.04=0.04 Ω-m @ BHT


Basic Log Analysis

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Find the Pay Zone!Find the Pay Zone!use use RwRw =0.04=0.04 Ω-m @ BHT

150 Ω-m 17%

Sw=9%

What about this?

Poor Hole Conditions make

interpretation difficult


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11. Dasar Analisa Log Kwantitatif