Well lod ,well Testing and mud logging Ghulam Abbas Abbasi
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Well logging records measurements made in boreholes to characterize underground formations. Key logs described include gamma ray, which measures natural radioactivity to identify shale; spontaneous potential, which indicates lithology; caliper, which measures borehole size; resistivity, which distinguishes water and hydrocarbon zones; and neutron, which determines porosity. Mud logging continuously monitors drilling mud and cuttings for gas readings. Well testing evaluates reservoir properties through daily tests and drill stem tests to determine flow rates and commercial potential.
Well lod ,well Testing and mud logging Ghulam Abbas Abbasi
- 2. TOPIC: WELLLOG& WELLTesting Assigned by: Sir Qamarudin khokhar Sir Ali Ghulam Sahito Presented by: GhulamAbbas Abbasi
- 3. What is well Logging Well log is a continuous record of measurement made in bore hole respond to variation in some physical properties of rocks through which the bore hole is drilled. The record of the measurements, typically a long strip of paper, is also called a log. continuous measurement of rock properties along the borehole made in bore.
- 5. Gamma Ray Log The gamma ray log is a record of a formations radioactivity. GR Log is a method of measuring the naturally occurring gamma radiation to characterized the rock or sediments in the bore hole or drilled hole. The radiation emanates from naturally occurring uranium ,thorium and potassium. The simple gamma ray log gives the radioactivity of the three elements combined unlike the spectral gamma ray log. Amongst the sediments ,shales have by far the strongest radiation. It is the reason that the simple gamma ray log has been called the ‘shale log’.
- 6. Gamma Ray Log Radioactivity of shales and clays. In petroleum borehole logging the commonest natural radioactivity (by volume) is found in shale's (clays). A high gamma ray value frequently means shale. A typical shale analyzed by a spectral gamma ray tool shows that each of the three elements U,TH,K is contributing and an analysis of shale's in general shows the relative contribution of each element to the overall radioactivity
- 7. Gamma Ray Log GR log reflects shale or clay content. Clean formations have low radioactivity level. Correlation between wells, Determination of bed boundaries, Evaluation of shale content within a formation, Mineral analysis, Depth control for log tie-ins, side-wall coring, or perforating. GR log can be run in both open and cased hole. Low radioactivity is plotted to the left. High radioactivity s plotted to the right.
- 8. SP LOG The spontaneous potential (SP) curve records the naturally occurring electrical potential (voltage) produced by the interaction of formation connate water, conductive drilling fluid, and shale The SP curve reflects a difference in the electrical potential between a movable electrode in the borehole and a fixed reference electrode at the surface Though the SP is used primarily as a lithology indicator and as a correlation tool, it has other uses as well: permeability indicator, shale volume indicator porosity indicator, and measurement of Rw (hence formation water salinity)
- 9. SP LOG Primary Usage of SP Log Differentiate shaly from non shaly Formation Detect the permeable beds. Locate bed boundaries for correlation. Determine the value of formation water resistivity(Rw). Plotted in 1st track on linear scale graph. Horizontal scale value ranges between -80 to 20MV. Can not be recorded in hole filled with non conductive mud. Sp is positive/reverse if the mud filtrate is more saline than formation water. Sp is negative/normal if the formation water is more saline than the mud filtrate. Permeable beds typically deflect the sp curve to left. The leftmost deflections indicate clean sands or carbonates.
- 10. Caliper log(Cali) A caliper log is a well logging tool that provides a continuous measurement of the size & shape of borehole along its depth. Caliper tool is a mechanical device with four arms, which expend to touch all sides of the well(borehole). In case of mud cake the diameter of hole will decrease. In case of washout the diameter of hole will increase. It is also used for measurement of the well caving protection. It is useful in QC and calculation of cement volume for casing.
- 13. Resistivity log Resistivity:- Resistance to flow of electric current. Logs measure and record the resistance offered by the rocks surrounding the borehole to the passage of an electric current It is a method of well logging that works by characterizing the rock or sediment in a borehole by measuring its electric resistivity. Resistivity is the inverse of conductivity, The ability to conduct electric current depends upon: The Volume of water, The Temperature of the formation, The Salinity of the formation
- 14. Resistivity log The Usage: Resistivity logs are electric logs which are used to: Determine Hydrocarbon versus Water-bearing zones, Indicate Permeable zones, Determine Resistivity Porosity. High resistivity indicates the Hydrocarbons Low resistivity indicates the Water.
- 15. Types of Resistivity log MSFL: Micro spherically focus log Log used to read invaded zone resistivity. LLS: Shallow/Medium matero log Log used to read transitional zone resistivity. LLD: Deep lateral log Log used to read un invaded zone resistivity.
- 16. Neutron Porosity Log The log The neutron log provides a continuous record of a formation’s reaction to fast neutron bombardment. It is quoted in term of neutron porosity units. The Neutron Log is primarily used to evaluate formation porosity. It is used to detect gas in certain situations, exploiting the lower hydrogen density, or hydrogen index. Low porosity and low density indicate the Gas factor.
- 17. The high speed atomic particles (neutron) as the tool lowered in the well or borehole. High speed neutron collide with two types of atoms in the rocks surrounding the well. High speed neutron collides with large rock atom it remains bounce with high speed & no loss of energy. High speed neutron collides with hydrogen atom (small atom) some energy remains absorbed by small atoms , & bounce slow speed. Hence slow speed moving neutron indicates the gas factor.
- 19. Mud Logging Collection of different mud and gas parameters. Many sensors are being used for the parameters of mud and gas. Sensors Temperature Density conductivity The different sensors sense and record in the computers present in Mud logging Unit OR data Unit.
- 20. Function of mud logging unit MUD PARAMETERS: Mud weight in & out Mud Temperature in & out Conductivity in & out Drilling Parameters: Hook Position (Depth Sensor) Hook Load (to measure the weight on bit) “WOB” Torque Stand-pipe pressure
- 24. Gas parameters: Total gas, H2S and CO2 Hydrocarbons components, (C1, C2, C3, iC4, nC4, iC5, nC5)
- 25. Well Testing Well testing is the technique & method for evolution of well conditions and reservoir characteristics. Well test highlights the hydrocarbons properties. It indicates the characteristics of the underground reservoir where hydrocarbons are trapped. It helps to identify the capacity of reservoir producing the hydrocarbons, such as Natural gas, Oil & Condensate(mixture).
- 26. There are basic well test type. i) Daily test i) DST i) Daily Test The daily test also termed as the ‘Flow Test’ This test is used to obtain the individual well rates separator divides the flow from the well into streams of the individual product typically OIL,GAS ,WATER and Condensate.
- 27. DRILL STEM TEST Dst is an procedure test for isolating and testing the Pressure, permeability, & Productive capacity of the formation. Its important for the measurement of Pressure & best way to obtaining the information about formation fluids (oil gas & water). Used to determine the fluids present and flow rate, Also used to determine the nature of reservoir. The main objective of DST is to evaluate the commercial zone (Potential zone) by perforation. It can be performed in open (without casing) & cased hole(Casing).