Lecture (3-4) Coring and Core Analysis.pdf
- 1. MD.ALIUR RAHMAN DEPTOF PME,JUST CORING AND ITS TYPES PME-2101: Reservoir and Fluid Properties Lecture_(3-4)
- 2. CORING PURPOSE OF CORING TYPES OF CORING 1 CONVENTIONAL CORING 2 SIDE WALL CORING DIFFERENCE BETWEEN CONVENTIONAL AND SIDE WALL CORING CORE HOLDER
- 3. Cores which extract from the formation /reservoir using special coring tools. Once the cores is cut ,they are captured and retrieved to the surface for analysis of different physical parameters. A core sample is a cylindrical section of (usually) a naturally occurring substance. Most core samples are obtained by drilling with special drills into the substance, for example sediment or rock, with a hollow steel tube called core drill. The hole made for the core sample is called the "core bowling".
- 4. CONTD….. In the coring process, the sample is pushed more or less intact into the tube. Removed from the tube in the laboratory, it is inspected and analyzed by different techniques and equipment depending on the type of data desired.
- 5. The purpose of getting cores is to obtained rock samples of sufficient size for : 1. Making reservoir analysis test to determined porosity, permeability, residual oil and water saturation (primary purpose of coring). 2. To establish the physical character of formation boundary. 3. To furnish paleontological data for age and facies correlation 4. To determined the structural attitude of the beds
- 6. There are two types of coring which are 1 Conventional coring 2 Side wall coring
- 7. Conventional coring is a methed of drilling and acquiring rock samples to retrieve the core samples. The complete rod string and core barrel has to be removed from the hole. When the bit is about to enter a formation of special interest. A service company may be brought in to take barrel cores. The coring tools consist of an annular diameter bit to cut the core and a hollow barrel to catch it.
- 8. Core samples may be of any length .but cores o f over 90 feet are hard to handle. A 60 feet core is average cores, which can be handle easily. A core diameter range from 11/8 to 5 inches with 4 inches being the most popular size for core analysis. Since it is costly and time consuming, also removing the cores is some time dangerous. since it is possible to swab the well and cause a blowout. So sidewall coring is most commonly used than conventional coring
- 9. 9 Rotary core barrel Coring String & Bit
- 11. Side wall coring is a methed used in zones where core recovery by conventional methed was less than expected or whereas cores were not obtained as drilling progressed. Side wall coring is useful in paleontological work. A side wall coring device is lowered into the hole on a wire line cable and a sample of the formation is taken at the desire depth.
- 12. This done by shooting a hollow bullet into the bore hole wall, then pulling it out of the well and bring up to the surface. There are as many as 30 bullets per guns and since two guns can be used. Up to sixty cores can be obtained during one run. If electric logs have been run previously , a spontaneous potential or gamma ray curve is used to determined gun position by direct log correlation
- 13. 13 Percussion Sidewall Coring gun
- 15. Conventional coring: Conventional coring provides large samples It is more better and more consistent representation of formation. It is better for heterogeneous rocks or for more complex lithology. Sidewall coring : Side wall coring provides smaller samples. It is less representative of heterogenous formation..
- 16. MINIMIZING CORE LOSSES DUE TO EROSION OF MATERIAL FROM FLUID CIRCULATION Bit discharge directed away from core Drilling fluid use kept to a minimum Polymer compounds added to drilling fluid Vibration of drill rod minimized Controlled advancement of the drill rod Core-catching devices installed
- 17. ROCK CORE LOGS To record all relevant information about the core and to make a field description Contains…… Percent core recovery Amount and location of core loss Depth of the beginning and ending of each core run
- 18. CORE HANDLING PROCEDURES Properly label and identify all samples Sample packaging depends on sample types Samples for chemical analysis should remain undisturbed, subsampled in the field and sealed immediately Chain of custody forms
- 19. ROCK CORE SAMPLES Rigid container required for transport Core placed into box left to right like top to bottom so it reads like a book Mechanical breaks in core should be distinguished from fractures Core can be labeled on core surface Depth, core loss points, fractures
- 20. Core Holder
- 21. WHAT IS A CORE HOLDER? WHY IS IT USED? “A portable apparatus provide on-site permeability measurements and formation evaluation by a core sample extracted from an underground reservoir.” CORE SAMPLE: A cylindrical rock (1-1/8“ to 5- 1/4" diameter and 30 to 60 ft long) sample taken from the formation for geological analysis to perform laboratory evaluation of basic properties.
- 22. TYPES OF CORE HOLDERS According to geometry: ---Vertical core holder ---horizontal core holder According to test: --resistivity core holder --acidizing core holder --Steam Flooding core holder For Permeability Measurements: --Gas (or Air) permeability measurement core holder --water (or brine, polymer) permeability measurement core holder
- 23. CORE HOLDERS FOR ROUTINE & SPECIAL CORE ANALYSIS (A) Hassler Type Core Holders (B) Biaxial Type Core Holders (C) Triaxial Type Core Holders
- 24. BIAXIAL TYPE CORE HOLDERS Biaxial type core holders are defined as core holders that have common radial and axial pressure applied to the core sample. These core holders are routinely used for gas and liquid permeability and other core flooding experiments.
- 25. TRIAXIAL TYPE CORE HOLDERS TCH Series core holders are triaxial type core holders. A triaxial type core holder is defined as a core holder in which the axial and radial pressures are independent of each other and can be varied during the test.
- 26. HASSLER TYPE CORE HOLDERS Core holders that have radial pressure applied to the core sample. Routinely used for gas and liquid permeability and other core flooding experiments. Spacers are provided to accommodate undersized cores. Distribution plugs are provided with a single inlet and outlet. The volume of all ports and flow lines are kept to a minimum so that accurate flow data can be determined.
- 27. LIMITATIONS IN MEASUREMENT Core sample may not be representative of the reservoir rock because of reservoir heterogeneity. Core recovery may be incomplete. Permeability of the core may be altered when it is cut, or when it is cleaned and dried in preparation for analysis. This problem is likely to occur when the rock contains reactive clays. Sampling process may be biased. There is a temptation to select the best parts of the core for analysis.
- 28. Thank You