Petroleum Eng

EOSC252

Lab2: Porosity Measurement (part 2)

1

Introduction

In this lab you will determine the porosity of your rock sample using the helium porosimeter shown on page 4. This device contains two cells, the sample cell and the expansion cell. Three valves, V1, V2 and V3 control the gas ow throughout the system:

• V1 connects the sample cell to the helium tank • V2 allows gas out of the system • V3 controls the ow between the sample cell and the expansion cell

A pressure sensor provides measurements of the gas pressure inside the sample cell. The pressure readings are displayed on a multimeter connected to the sensor (in units of Volts). To nd the porosity using the helium porosimeter, we will apply Boyle's law. This law states that, under conditions of xed gas quantity and constant temperature, the product of the pressure and volume stay constant. Boyle's law is expressed as follows:

P1 V1 = P2 V2 .

2

Experimental Procedure

Be sure to record exactly what you do, what readings you take, and what valves you open or close at various stages in this experiment. THINK ABOUT WHAT PARTS OF THE SYSTEM ARE CONNECTED AT ALL TIMES.

****DANGER!!!! NEVER OPEN THE SYSTEM WITHOUT FIRST LETTING OUT THE GAS SO THE PRESSURE DROPS TO ZERO.****

1

1. Measure the length and the diameter of your sample. Repeat this 5 times, taking measurements at dierent points around your sample. 1 2 3 4 5 Average Diameter ( )

± ±

Length (

)

2. Determine the volume of the sample cell, Vcell , and expansion cell, Vexp , of the porosimeter (a) Ensure V1 is closed tightly. Open V2 and V3. Wait until the reading on the multimeter is stable. Record the voltage corresponding to the atmospheric pressure. (b) Ensure V2 and V3 are closed tightly. Open V1 to let gas ow into sample cell only. When the reading on multimeter stabilizes, close V1. Record the reading. (c) Ensure V1 and V2 are closed tightly. Open V3 to let the gas ow into the expansion cell. Record the...