intro rock properties and their other properties

rock properties

1. Introduction What are the reservoir rock properties? The importance of reservoir rock & fluid properties How fluids flow through the reservoir rock and how this flow can be altered to produce greater recovery and profits Provides good understanding in reservoir management, Simulation and EOR, etc.

2. Reservoir Fluid Properties? What are reservoir fluids? Crude oil Natural gas or Drinkable water?

3. Reservoir Rocks Oil created by the source rock won’t be useful unless it winds up being stored in an easily accessible container, a rock that has room to “suck it up” A reservoir rock is a place that oil migrates to and is held underground. Examples of reservoir rocks includes: Sandstones Limestone and /or Carbonate rocks

4. Characteristics of Reservoir Rocks A good reservoir rock must have porosity in which petroleum can exist. Even though a reservoir rock looks solid to the naked eye, a microscopic examination reveals the existence of tiny openings in the rock, called pores. Another characteristics of reservoir rock is that it must be permeable . That’s the pores of the rock must be connected together so that hydrocarbons can move from one pore to another

5. Source of data: Coring Coring are processes used to recover formation samples from petroleum reservoirs. Reservoir rock samples are used for reservoir description and definition, reservoir characterization and to enhance both geological petrophysical nature of the reservoir. Physical sample of reservoir rock core is essential to evaluate the two most significant characteristics: the capacity and ability of the reservoir rock to store and conduct petroleum fluids through the matrix. In addition, data on formation’s lithology and production potential are obtained through coring program.

6. ROCK MATRIX AND PORE SPACE Rock matrix Water Oil and/or gas

7. Framework Matrix Cement Pores Sand (and Silt) Size Detrital Grains Silt and Clay Size Detrital Material Material Precipitated Post- Depositionally , During Burial. Cements Fill Pores and Replace Framework Grains Voids Among the Above Components FOUR MAJOR COMPONENTS OF SANDSTONE

8. MATRIX FRAMEWORK (QUARTZ) FRAMEWORK (FELDSPAR) PORE 0.25 mm CEMENT FOUR COMPONENTS OF SANDSTONE

9. PDC Cutters Fluid vent Drill collar connection Inner barrel Outer barrel Thrust bearing Core retaining ring Core bit CORING ASSEMBLY AND CORE BIT

10. Unlike a normal drill bit, which crushes the rock into small pieces, a core bit can be visualized as a hollow cylinder with cutters on the outside. The cylinder of rock that is cut by the bit is retained within the core barrel by an arrangement of steel fingers or slips. Core diameters are typically from three to seven inches and are usually about 90 feet long. Coring Whole core sampler Side-wall core sampler

11. Whole Core Photograph, Misoa “C” Sandstone, Venezuela WHOLE CORE Photo by W. Ayers

12. SIDEWALL SAMPLING GUN Core bullets Core sample Formation rock The sidewall sampling tool can be used to obtain small plugs from the formation. The tool is run on a wireline after the hole has been drilled. Some 20 to 30 bullets are fired from each gun at different depths. The hollow bullet will penetrate the formation and a rock sample will be trapped inside the steel cylinder. When the tool is pulled upwards, wires connected to the gun pull the bullet and sample from the borehole wall. Sidewall cores are useful for identifying hydrocarbons zones, when viewed under UV light. Qualitative inspection of porosity is possible; however, the cores may have been crushed during the collection process, so quantitative sampling of porosity is questionable.

13. SIDEWALL CORING TOOL Coring bit Samples A newer wireline tool actually drills a plug out of the borehole wall, thus avoiding crushing of the sample. Up to 20 samples can be individually cut and are stored inside the tool.

14. WHOLE CORE ANALYSIS vs. PLUGS OR SIDEWALL CORES WHOLE CORE Provides larger samples Better and more consistent representation of formation Better for heterogeneous rocks or for more complex lithologies

15. Smaller samples Less representative of heterogeneous formations Within 1 to 2% of whole cores for medium-to high-porosity formation In low-porosity formations,  from core plugs tends to be much greater than  from whole cores Scalar effects in fractured reservoirs WHOLE CORE ANALYSIS vs. PLUGS OR SIDEWALL CORES PLUGS OR SIDEWALL CORES

16. Coring core plug whole core

17. INFORMATION FROM CORES Porosity Horizontal permeability to air Grain density Vertical permeability to air Relative permeability Capillary pressure Cementation exponent (m) and saturation exponent (n) Standard Analysis Special Core Analysis * Allows calibration of wireline log results