Download - 04.SP LOG
-
8/18/2019 04.SP LOG
1/8
WELL LOGGING ANALYSIS.WELL LOGGING ANALYSIS.
04.Spontaneous 04.Spontaneous Potential.Potential.
Mustoto Mustoto Moehadi Moehadi ..HP. 085814457579 HP. 085814457579
5MT – Oil & Gas Business Series.
5MT - Oil & Gas Business Course.
Spontaneous Potential.
2
Dihasilkan dari adanyaperbedaan tegangan dari
suatu elektroda yangberjalan didalam lubang bor
dengan elektroda yang
tetap dipermukaan, dimana
elektroda tersebut melewati
berbagai jenis batuan yang
berbeda sifat serta isi yang
terkandung didalamnya,
dalam satuan millivolt.
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG
5MT - Oil & Gas Business Course.
Spontaneous Potential.
3
What is SP?What is SP? (Spontaneous Potential) (Spontaneous Potential)
A Voltage measurement between a down-
hole Electrode and a Surface Electrode (also
called a Fish)
SP Voltage was discovered by accidentwhen an Engineer running an Electrical Tool
was pulling out the Tool (without any Tool
Power applied) and forgot to STOP the Log
recording
SP Voltage is an extremely SMALL voltage
and develops in Open Hole with Water based
Muds only (due to differences in
concentration of Ions between Drilling Mudand Formation Water)
5MT - Oil & Gas Business Course.
Spontaneous Potential.
4
What causes the SP voltage? What causes the SP voltage?
Electro-chemical (Ec) sources (Primary reason, produces > 95% ofthe Total SP signal)
Electro-kinetic (Ek) sources (rare and small signal)
Electro-Chemical (Ec)
sources are further
divided into
a. Liquid Junction
Potential (E j)
b. Membrane Potential
(Em)
OREc = E j + Em
-
8/18/2019 04.SP LOG
2/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
5
Liquid Junction Potential Liquid Junction Potential
Chloride Ions Cl- are more mobile, therefore they
quickly migrate from Higher concentration C1 tolower concentration C2, leaving the Sodium Ions
Na+ behind
This results in charge imbalance and a Potential to
appear at the Liquid Juncti on
5MT - Oil & Gas Business Course.
Spontaneous Potential.
6
Membrane Potential Membrane Potential
Shales have negative charge on their crystal lattice frame,therefore they attract Sodium Na+ ions and repel Chloride Cl-ions and act like Ion filters
These Na+ ions then migrate thru the Shale and accumulate onthe Borehole Shale boundary.
5MT - Oil & Gas Business Course.
Spontaneous Potential.
7
Combining the Two effects Combining the Two effects
If we now pass an electrode past the formation we would see negativedeflection in front of the permeable zone and a positive deflection in
front of the Shale The magnitude of the deflection will depend on the contrast of salinitiesof the two liquids
We measure the Total deflection from the Shale Base line
++
+ _ _ _ _ _
Shale
base
line
5MT - Oil & Gas Business Course.
Spontaneous Potential.
8
SHALE LINE dan SAND LINE
Adalah gambaran kurva SP terhadap lapisanshale yang pada umumnya konstan dan akanmengikuti suatu garis lurus.
Sedang untuk lapisan yang porouspermeable defleksinya akan menjauhi shalebase li ne pada lapisan yang tebal .Penyimpangan ini mencapai suatu hargadef leksi yang konstan yang biasa disebutsebagai “ Sand Line”.
Peny impangan kurva SP b isa kearah k irimaupun kanan tergantung pada salinitasrelatif dari air formasi dan filtrate sumur.
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG
-
8/18/2019 04.SP LOG
3/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
9
Magnitude and Polarity of Sp deflectionMagnitude and Polarity of Sp deflection
depends on the Contrast in Salinities depends on the Contrast in Salinities
5MT - Oil & Gas Business Course.
Spontaneous Potential.
10
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG
5MT - Oil & Gas Business Course.
Spontaneous Potential.
11
KURVA SP AKAN
TERBENTUK BILA.
Terdapat shale dan lapisan
yang permeable.
Adanya perbedaan salin itasantara air formasi (Rw) dan
filtrat lumpur (Rmf).
Terjadi invasi dari fi ltrat.
Fluida didalam sumur
konduktif.
Sumur tidak diselubungi pipa.
Kontrak elektrik terjadi antara
elektroda acuan dengan
elektroda dalam sumur.
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG
5MT - Oil & Gas Business Course.
Spontaneous Potential.
12
STATIK SPONTANEOUS POTENSIAL.
Apabila pengukuran SP melalui lapisan batuan yang cukup
tebal serta dengan kondisi bersih, maka defleksi kurva SP
akan mencapai maksimum, bila defleksi SP tidak dipengaruhioleh kandungan shale yang ada dalam batuan tersebut.
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG
-
8/18/2019 04.SP LOG
4/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
13
Membedakan lapisan/batuan impermeable (shale)
dengan permeable (non-shale).
Menentukan batas litologi dan ketebalan batuan.
Membantu untuk menentukan lingkungan
pengendapan.
Kwalitatif; banyak shale pada lapisan batuan
permeable.
Kwantitatif; menentukan Rw.
Korelasi antar sumur-sumur geologi.
Kegunaan Kegunaan SP Log.SP Log.
5MT - Oil & Gas Business Course.
Spontaneous Potential.
14
FACTORS AFFECTING THE SP RESPONSE FACTORS AFFECTING THE SP RESPONSE
Hydrocarbons: reduce the SP deflection.
Shaliness: reduces the SP deflection.
Bed thickness: thin beds do not develop a full SPdeflection.
Permeability: low permeability zones will have a veryhigh invasion diameter, so it may be impossible to
read the Junction Potential, hence SP readings may
be low
5MT - Oil & Gas Business Course.
Spontaneous Potential.
15
Dibawah ini adalah sejumlah pembatasan darikehandalan metode ini:
1. Komponen elektrokinetik dari SP diabaikan.
2. Contoh Rmf yang buruk (contoh filtrasi lumpur yang tidak baik).
3. Hubungan antara Rwe-Rw dan Rmfe-Rmf,khususnya pada Rw yang tinggi.
Sehingga penggunaan SP untuk menentukan Rwhanya boleh dilakukan bila metode lain tidakberlaku.
Ketidak Ketidak Pastian Pastian SP Log.SP Log.
5MT - Oil & Gas Business Course.
Spontaneous Potential.
16
SP Applications SP Applications
Depth correlation (SP curve behaves very
much like the Gamma Ray curve)
Identify ing Bed boundaries
Lithology Indicator (Shale or non-Shale)Permeability Indicator
Volume of Shale (Vsh) indicator
Rw Calculation
-
8/18/2019 04.SP LOG
5/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
17
Problems recording SP Problems recording SP
Drum Magnetism, Measuring Head Magnetism
causes cyclic SP
Cable conductor leakage
Running water on SP Fish
Welding or any heavy Electrical activity at Rig
Stray ground currents and voltages
Bi-metallism
5MT - Oil & Gas Business Course.
Spontaneous Potential.
18
SP LOG SAMPLE and The Effect Magnetism on SP SP LOG SAMPLE and The Effect Magnetism on SP
5MT - Oil & Gas Business Course.
Spontaneous Potential.
19
1. Baca harga Ssp.
2. Tentukan Rmfe. Jika Rmf pada 75 deg F>0.1 Ohm, maka Rmfe=0.85XRmf.
Jika Rmf pada 75 deg F
-
8/18/2019 04.SP LOG
6/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
21
10.SP 10.SP
5MT - Oil & Gas Business Course.
Spontaneous Potential.
22
5MT - Oil & Gas Business Course.
Spontaneous Potential.
23
11.Sp 11.Sp
5MT - Oil & Gas Business Course.
Spontaneous Potential.
24
11.SP 11.SP
-
8/18/2019 04.SP LOG
7/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
25
12.SP 12.SP
5MT - Oil & Gas Business Course.
Spontaneous Potential.
26
12.SP 12.SP
5MT - Oil & Gas Business Course.
Spontaneous Potential.
27
13.Rmf/Rwe f/ SP 13.Rmf/Rwe f/ SP
5MT - Oil & Gas Business Course.
Spontaneous Potential.
28
13.Rmf/Rwe 13.Rmf/Rwe
-
8/18/2019 04.SP LOG
8/8
5MT - Oil & Gas Business Course.
Spontaneous Potential.
29
14.Rw 14.Rw
5MT - Oil & Gas Business Course.
Spontaneous Potential.
30
14.Rw 14.Rw
5MT - Oil & Gas Business Course.
Spontaneous Potential.
31 5MT - Oil & Gas Business Course.
Spontaneous Potential.
32
MOUNCE & RUST;
Mempelajari rantai aliran dari suatu sistim yang terdiri dari
2 elektrolit dengan konsentrasi berbeda dengan shale.Ternyata arus yang mengalir dalam sistim tergantung padakonsentrasi kedua elektrolit. Gambar jo lali
SPONTANECOUS POTENTIAL LOG SPONTANECOUS POTENTIAL LOG