ABSTRACT which the pore spaces are interconnected.

ABSTRACT Porosityis one of the two most important properties of a reservoir rock, of which theother is permeability. Porosity determines a reservoirs storage capacity. It maybe defined as the ratio of void space, commonly called pore volume, to bulkvolume and is usually reported as either fraction or a percentage.

TheOFITE MODEL 350 porosimeter was designed to rapidly and accurately measure theeffective porosity of a core sample. The effective porosity is the percentageof void within a solid media in which the pore spaces are interconnected. It isimperative to accurately measure the effective porosity of a petroleumreservoir when estimating the amount of recoverable oil within a producingformation.Inthis experiment, OFITE MODEL 350 porosimeter was used to estimate the effectiveporosity of a core sample. The core sample had a diameter of 3.

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7cm and was 6.3cmlong. The effective porosity was later estimated to be 22.2%. CHAPTER 1: INTRODUCTION Porositycan be defined as the percentage of void within a solid media.

Almost allhydrocarbon reservoirs are composed of sedimentary rocks in which porosityvalues 10 to 40% in sandstones and 5 to 25%in carbonates (M. Peter Cone & Kersey).Discrepanciesoften exist between laboratory determined porosity values and porositiesderived from downhole logs. Many of these discrepancies can however beexplained by noting differences in the definition and assessment of porosity (M. Peter Cone & Kersey).Porositycan be categorized as total or effective porosity. Total porosity is the ratioof all the pore spaces in the rock to the bulk volume of the rock, whileeffective porosity is the ratio of interconnected void spaces to the bulkvolume (Torsaeter & Abtahi, 2000). Thus, only theeffective porosity contains fluids that can be produced from wells (Torsaeter & Abtahi, 2000).

Figure1: Sketch of Cross Section of Reservoir Rock CHAPTER 2: EXPERIMENTALAPPARATUS & MATERIALS2.0 INTRODUCTIONForthe purpose of this experiment, the equipment used includes the core porosimeterand the Vernier caliper, while the material used was a core plug.  2.

1 CORE POROSIMETER Theporosimeter is an instrument used for measuring the pore volume, and hence theporosity of a core sample. Pore volume is obtained from thedifference between bulk volume and grain volume (Schlumberger Oilfield Glossary, n.d.).

                            Figure2: Core porosimeter (OFITE MODEL 350 CORE POP) 2.2 VERNIER CALIPERThisis a measuring instrument that consists of an L-shaped frame with a linearscale along its longer arm and an L-shaped sliding attachment with a vernier, usedto read directly the dimension of an object (in this case, the core plug)represented by the separation between the inner or outer edges of the twoshorter arms (American Heritage Dictionaries, 2011). Figure3: Vernier Caliper2.

3 CORE PLUGThisis a plug or sample taken from conventional core for analysis. Core plugs aretypically 2.5 to 3.8cm in diameter and about 5cm long or more (Schlumberger oilfield glossary, n.d.).                    Figure4: Core plugsCHAPTER 3: EXPERIMENTAL PROCEDURE Theprocedure for this experiment (Porosity determination using core porosimeter)was as follows:1.

      Beforecommencement of experiment, I placed all the valves in a vertical condition andmade sure the regulator in the front panel was rotated fully clockwise.2.      Iturned the unit on and allowed it to warm up for 5-10 minutes.3.      Ithen measured and recorded the diameter and length of the core using a verniercaliper.4.      Iunscrewed the sample holder and inserted the core specimen.

I then screwed thesample holder back into place.5.      Next,I turned the P2 test valve to the off position.6.      Ithen rotated the regulator clockwise until the pressure read 180psi.7.

      Ithen turned the P1 lock in valve to the off position and allowed P1 tostabilize before recording the value. CHAPTER 4: RESULT DISCUSSION 4.1 CONSTANTS OF THEPOROSIMETERV1 = 60.18cm³V2 = 165.31cm³ 4.

2 RECORDED PARAMETERSInitial Pressure Value, P1= 180.65psiFinal Pressure Value andExpansion, P2 = 96.5psiDiameter, D = 3.7cmLength, L = 6.3cm 4.

3 CALCULATED PARAMETERS4.3.1 CORE BULK VOLUME, VBVB= ………………………………………………………………………………….. (4.

1)Where:VB= Bulk VolumeD= DiameterL= Length  VB =  = 67.7cm³ 4.3.2 V3V3=  ………………………………………………………………………………… (4.2)Where: P1 = Initial PressureValue P2 = Final Pressure Valueand Expansion V1 = Constant ofPorosimeter  V3 =  =112.7cm³ 4.

3.3 CORE GRAINVOLUME, VGVG  = V2-V3 …………………………………………………………………………………..(4.3)Where:VG= Core Grain VolumeV2= Constant of the Porosimeter  VG  = 165.31 – 112.7 = 52.

7cm³ 4.3.4 CORE PORE VOLUME, VPVP  = VB – VG……………………………………………………………………………..

.…. (4.4)Where:VB= Bulk VolumeVG = CoreGrain Volume VP  = 67.7 – 52.7 = 15cm³ 4.3.5 POROSITY,  =  * 100 …………………………………………………………………………………(4.5)Where:VB= Bulk VolumeVP= Core Pore Volume  =  * 100=22.2%CHAPTER 5: CONCLUSION Inconclusion, the porosimeter rapidly and accurately measures the effectiveporosity of a core sample, which was measured as 22.2% for a core sample oflength 6.3cm and diameter 3.7cm.The knowledge of theeffective porosity which has been gained is imperative to accurately measure theeffective porosity of a petroleum reservoir when estimating the amount ofrecoverable oil within a producing formation