Laterologs

ppt

1. Laterolog 1 Ade Rama Tanjung Putra ( 1506741524 ) Ridho Irsyad Fauzan ( 1506721440 )

2. Outline 2 LATEROLOGS

3. Logging The identification of reservoir The estimation of hydrocarbon in place. The estimation of recoverable hydrocarbon To identify the productive zones of hydrocarbon. To define the petrophysical parameters like porosity, permeability, hydrocarbon saturation and lithology of zones . To determine depth, thickness, formation temperature and pressure of a reservoir. To distinguish between oil, gas and water zones in a reservoir. To measure hydrocarbon mobility. Well logs 3 A. Introduction

4. Physical parameters that can be recorded : 1) Resistivity Logs - Induction log - Later o log 2) Porosity/Radioactive Logs. 3) Sonic/Acoustic Log 4) Sampling and coring 5) Cement evaluation Log 6) Production Logs. 4 Target A. Introduction

5. ELECTRICAL LOGGING The induction log actually measures conductivity, and hence is sometimes called the conductivity log. The modern tool for measuring resistivity in high salinity (low resistivity) muds is the laterolog , which focuses its current into a thin sheet to improve vertical resolution and penetration depth. The laterologs measure resistivity in the conventional sense, and are usually referred to as resistivity tools. 5 A. Introduction

6. RESISTIVITY LOGGING Resistivity is one of the most variable physical properties of materials and has proven to be the most useful geophysical parameter in the search for hydrocarbons resources. The resistivity of a substance is its ability to impede the flow of electric current through the substance. 6 A. Introduction

7. The electrical tools also have a number of qualitative uses, principle of which are : ( i ) indications of lithology, ( ii) facies and electro- facies analysis, ( iii) correlation, ( iv) determination of overpressure, determination of shale porosity, ( v) indications of compaction, and the investigation of source rocks. 7 B . Principle uses of electrical log

8. The degree to which the sandstones have higher resistivities depends upon : ( i ) their porosity, ( ii) their pore geometries, ( iii) the resistivity of the formation water, ( iv) the water, oil and gas saturations (oil and gas are taken to have infinite resistivity). 8 C. Typical responses of an electrical tool

9. 9 C. Typical responses of an electrical tool

10. 10 D. Old electrical logs

11. The current density varies inversely with the radial distance and can be calculated from: Current density Current density = I / (2 * PI * R * T) Where,   I = total current intensity (amperes)   T = thickness of measure current disc (meters)   R = radial distance (meters) Resistivity of the formation Rt = K * V / I (same as ES log except K is different) Where   V = potential of measure electrode (volts)   I = current flow from measure electrode (amperes)   K = a calibration constant defined by the geometry of the electrode spacing 11

12. L aterolog was put into service in 1949 as a replacement for the ES Log in salt mud environments. It was another invention by Henry Doll of Schlumberger. Competitive tool designs were called Guard Logs or Focused Logs. The objective was to focus the current from the tool into the rock better than could be accomplished with the ES Log. 12 E. Modern r esistivity logs ( Laterolog )

13. Laterologs work best in saltier muds or in normal muds in high resistivity formations. They will not work in air filled or cased holes The laterolog is a direct current (DC) tool based on Ohm's Law . The tools have been designed to produce reliable resistivity measurements in boreholes containing highly saline drilling fluids and/or when surrounded by highly resistive rocks. 13

14. The logging current is prevented from flowing up and down within the drilling fluid by placing focusing electrodes (A1 and A2) on both sides of a central measure electrode A0, as illustrated below. The focusing electrodes force measure current to flow only in the lateral direction, perpendicular to the axis of the logging device. 14

15. 15 E. Modern r esistivity logs ( Laterolog ) E.1. Basic laterologs

16. 16 E. Modern r esistivity logs ( Laterolog ) E.2 Dual laterologs

17. Dual Laterolog (DLL) Dual Laterolog instruments are electrode tools designed to produce reliable formation resistivity measurements in boreholes containing saline drilling fluids. The Dual Laterolog instrument simultaneously produces a deep investigation resistivity and a shallow investigation resistivity measurement. 17

18. The DLL produces two measurements, the laterolog shallow (LLS), and laterologdeep (LLD). The dual laterolog (DLL) is the latest version of the laterolog . As its name implies, it is a combination of two tools, and can be run in a deep penetration ( LLd ) and shallow penetration (LLs) mode. These are now commonly run simultaneously and together with an additional very shallow penetration device. 18

19. LLd Mode T he tool operates just like a LL7 tool but with the same bucking currents that are emitted from the A 1 electrodes The result of this is to focus the current from the central electrode . 19

20. LLs Mode T he bucking current must veer away from the pathway into the formation, and back towards the tool A2 electrodes, and hence cannot constrain (focus) the current being emitted from the central electrode as much. 20

21. Both modes of the dual laterolog have a bed resolution of 2 feet, and a sensitivity of 0.2 to 20,000 Ωm. To achieve this sensitivity both the current and voltage are varied during the measurement, keeping their product (the power) constant. 21

22. 22 E. Modern r esistivity logs ( Laterolog ) E.3 Spherically focus log

23. 23 F . Micro-Resistivity logs F.1 Micro log The microlog (ML) is a rubber pad with three button electrodes placed in a line with   a 1 inch spacing. known current is emitted from   electrode A, and the potential differences between electrodes M 1 and M 2 and between M 2 and a surface electrode are measured .

24. The microlaterolog (MLL) is the micro-scale version of the laterolog , and hence incorporates a current focussing system. The tool is pad mounted, and has a central button electrode that emits a known measurement current surrounded coaxially by two ringshaped monitoring electrodes, and a ring-shaped guard electrode that produces a bucking current as in the LLD. 24 F . Micro-Resistivity logs F.2 Micro laterolog

25. 25 F . Micro-Resistivity logs F.3 Proximity log The proximity log (PL) was developed from the MLL to overcome problems with mudcakes over 3 / 8 ” thick, and is used to measure R XO .

26. 26 F . Micro-Resistivity logs F.4 Micro spherically focused logs The micro spherically focussed log (MSFL) is commonly run with the DLL on one of its stabilizing pads for the purpose of measuring R XO .

27. 27 G.Uses of electrical log G.1 Recognition of hydrocarbon G.2 Calculation of water saturation G.3 Other application

28. Application of Dual Lateralog Determine formation resistivity in saline mud systems and high formation resistivities Qualitatively indicate permeability Formation evaluation, including hydrocarbon/water contact 28

29. 29 G.Uses of electrical log G.1 Recognition of hydrocarbon

30. 30 G.Uses of electrical log G.1 Recognition of hydrocarbon

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32. High resolution laterolog showing deep invasion and high resolution image. 32

33. Well Log Response Chart ( Pertamina , 2000) 33

34. Conclusion Resistivity is one of the most variable physical properties of materials and has proven to be the most useful geophysical parameter. Laterologs work best in saltier muds or in normal muds in high resistivity formations. Dual Laterolog instruments are electrode tools designed to produce reliable formation resistivity measurements in boreholes containing saline drilling fluids. 34

35. References Shankar , Shri S. WELL LOGGING TECHNIQUES AND FORMATION EVALUATION-AN OVER VIEW https://www.spec2000.net/07-latlog.htm 35

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