Sample Essay on Petroleum Geology

Currently there are several methods of experimenting in the process of highlighting petroleum quality.During a recent class in PNGE 332 class-Petroleum Properties and Phase Behavior a new concept of computer modeling group (CMG) was introduced and used. The use of Builder Win 2011.10, which is the first version of the CMG-Launcher, developed in 2011 was the computer software used in this experiment. The primary reason behind using this new concept was to develop a model that would give effective results without the two-yearcondensation by using computer modeling. This manuscript shows a number of graphical representation that are based on temperature as well as pressure. In order to perform the experiment a cylindrical model was developed containing a single porosity that was used in the computer simulator. The model comprised of seven layers with an inner radius of 0.25 ft and an outer radius of 500 ft. Of the seven layer, the thickest layer measured 7100 ft raising from 7040 ft. The temperature as well as pressure in the experiment were consistent at 320 °F at as well as 1500 psi respectively. Though the pressure was consistent, its determinant was the rock compressibility (CPOR) which was set at (5e-6 1/ psi). The resultant of the experiment was calculated by using thePing Robinson equation of state.  In the field of thermodynamics, there is a constant need to provide mathematical proof referring to the relationship between several functions that are associated with matter for instance temperature, pressure, volume, as wellas internal energy. The Ping Robinson equation used in this experiment is based on finding the co-existence of light and heavy hydrocarbons in water-oil as based on the effect of temprature and water.Below is a table showing the retrograde gas with the components shown.

Components Compositions
C4 70
N-C4 20
N-C7 5
N-C10 5
Sum 100

At the end of the experiment calculations, the data highlighted three dissimilar oil as well as gas zones were present. The simulation saw based on a duration of two years condensation. The pressure and temperature parameters use will be set to mimic the time.

Theory, Concepts and Objectives of the Experiment

            The test represented in this paper was conducted using computer modeling group to develop a model that maximizes as well as gives an accurate reading avoiding years of consecutive condensation. In order to find the required results the Peng Robinson equation of state was used in the simulation. However, the equation required several assumptions namely

  1. Thermodynamic equilibrium is instantaneous”
  2. Joule-Thomson effects are neglected as well as pressure changes appear in  isothermally”
  3. Mercury is incompressible”
  4. The tubing in the system has no value”

It should be noted that in order several terms should be defined in order to comprehend the significance of this paper. For example, the critical pressure which is defined as the pressure the is above and beyond the limits the liquid as well as gas cannot harmonize.  On the other hand critical temperature is defined as the temperature that beyond which a gas cannot condensed to a liquid irrespective of the pressure excreted. Additionally, another noteworthy term to be defined is the bubble point, which is referred to as the last point at which the first gasses evaporate from liquid state from small bubbles. Another term known as the dew point, which drop-like liquids remain in liquid from after evaporation.

The production of gases is determinant on several factors for instance porosity as well as permeability. These two aspects are significant in either increasing or reducing the production of gases as well as oil. In the above mentioned test the permeability as well as porosity was 50 md as well as 15% respectively. Reducing porosity aided in the determination of gaseous flow. Additionally the pressure was set to a level that encouraged dew point hence maintaining the condensation. Consequent to these conditions production of gases was sustained at the maximum. During the plotting of a 2-phase figure, the critical temperature level was 300 °F ∓ 10.  Consequently, this was below the reservoir temperature of 320 °F finally resulting to the production of retrograded gas.

Figure 1: the figure above is a representation of a typical gas line of isothermal reduction representing reservoir pressure, 123, as well as surface separator settings. From figure 1, the critical point is placed on the extreme left of the limits. The critical temperature is higher than the reservoir temperature of by apparently 20 °F. On the other hand, the reservoir temperature is lower than the cricondentherm consequently, resulting into having both light hydrocarbons as well as several heavy hydrocarbons in the same atmosphere. The lesser limit in the prior production of gas to oil ratio for a retrograde was roughly 3300scf/STB. Nonetheless, the preliminary GOR ration indicated a rich retrograde gas subsequently leading to the condensation of 35%, which is highly sufficient for the reservoir volume. Nevertheless, the liquid would occasionally trickle in the reservoir suggesting more gases and lesser waste in liquid form. In the course of conducting the experiment the pressure for the reservoir was reduced lower than the dew point leading to the increase of API to 60 than the previously indicated 40 of the retrograde gas simulation.

Experimental procedure:

For this test the Builder Win 2011.10, which is the first version of the CMG-Launcher, developed in 2011. The experiment date was set to be on to 1-1-2012 after the Cylindrical Grid was developed as well as the temperature variations were determined. The different varieties in characteristics of the cylindrical configuration were defined by providing the information below.

Porosity and permeability set at 15%, as well as 50 md respectively. The well was made out of seven layer with the first layer measuring 7040 ft in thickness increasing by 10ft per layer making the last layer 7100 ft. The next step was setting specific rock compressibility levels which were the CPOR (Rock Compressibility)was set at 5e-6 1/psi; PRPOR (rock compressibility pressure) was 1000 psi; TRPOR (rock compressibility temperature) was320 F.  Other measurable parameters indicated were CTPOR, whichrepresents the coefficients of thermal expansion set at 0 (1/F); CPTPOR which is the pressure and temperature cross-term coefficients of porosity placed at 0 (1/psi*F). From the result achieved after setting up the above test limits were analyzed using the Peng-Robinson equation after accessing the TRES (Reservoir temperature).

When the simulation was initially run the additional components required were selected and the included CH4 (16), NC4 (58), NC7 (100) and NC10. The data represented was highly significant in making a 2 phase diagram sowing temperature as well as pressure curve that is shown below.

Figure 2: 2 phase diagram

The figure shown represents a 2-phase diagram showing the critical temperature as well as the reservoir temperature estimated at 300 °F and 320 °F respectively. The above estimates show that the reservoir temperature is slightly higher than the critical temperature this is to allow the retrograde gas flow to the reservoir tank at ease.

The data for water-oil and gas-liquid were similarly identified with the reference pressure and depth were set at  3000 psi as well as 7040 ft correspondingly with the base whole pressure set at 1500 psi and the 2 year simulation was set. At the end of the experiment, a 3-D result was attained with the separation highlighted after the CMG simulator was run. In order for the saturation profile to be achieved the outcomes had to beexported as a file ending as .txt  containing both xyz values x representing a dissimilar radius of the reservoir while Z referring to oil separation. Consequently,in the simulation the separation profile showed three dissimilar zones were highlighted majorly because of the pressure placed in the simulation. After several months and the saturation was determined on a step by step basis.

Figure 3: Saturation Zones

The figure above represents the graphical movements of separation of the water-oil and gas-liquid in three zones after running the simulation program getting xyz values after 6 to 8 times from a 2 years reproduction.

Figure 4: Saturation Profile

The figure above is a representation of the saturation profile of the gas production aligned besides the duration the simulation was let to run the first portion of high saturation is placed to show the production in zone 1. The higher the pressure above the dew point the higher mthe amount of gasses. Additionally as time passes and the pressure gradually falls below the dew point the lesser the saturation and less gasses.

As shown in figure 3 the separation is highly dependent on pressure coefficients. The first zone highlighted in red shows separation when the pressure is beyondthe dew point.  The second zone highlighted in light blue represents separation when the pressure is well lower than the dew point as well ashigh condensate permeation. Lastly, it is evident from the chart that the oil saturation rises with time owing to the pressure declining.

Analysis and Discussion

From figure 4, the saturation profile zone 1 indication where the pressure is well higher than the dew point highlights no oil saturation consequently concentrated production of gases. Zone 2 representing lower pressure than dew point the production will only consist of gases saturation owing to the lower aggregate condensate that exists below the critical liquid saturation. In zone 3 representing pressure, further below dew point than zone 2 as well as a higher condensate saturation the results showed lower gases production due to it mixture with oil.  From the above results,it is clear that the pressure coefficients are the primary aspect that determines the production of gases. Temperature though secondary also determines the dew point and the more time and consistency in pressure and heat as well as resources placed on the simulator showed the production of gasses.So, in order to increase the productivity of the gas, the pressure has to be sustains above the dew point. The charts as well as the numbers showed that as the pressure decreased the amount of liquidation increase and this altered the flow of the gasses.


The paper above represents and experiment conducted on extracting retrograde gas from a mixture of oil and water. The use of a computer simulator version of Builder Win 2011.10, or what has been highlighted as the CMG. The use of Permeability as well porosity to affect the effectiveness of the condensation process determining the amount of gasses to be produced. The design presented was cylindrical in nature containing seven layers with varying thickness. The model was then set to contain retrograded gas with a temperature of 300 °F, which was 20 °F lower that the reservoir temperature this is with the inclusion of 60 °API pressure. With a variety of rock compressibility indicated the simulation representing 2 years condensation was conducted highlighting three zones several checks. The pressure above as well as below the dew point separated the three zones. The first zone representing pressure above the dew point showed a higher production of gasses. On the other hand, zone 2, which represented pressure slightly below the dew point, showed a lower production of gases a factor that got even worse in zone 3. The mixture of oil and gases made it hard for the resulting fumes to move to the reservoir. Additional research showed that as pressure decreased with time oil separation increased increasing decreasing the production of gasses. To avoid damage of the separation zone the simulation showed that the pressure has to be above the dew point

Work Cited

Fussell, D. D. “Single-well performance predictions for gas condensate reservoirs.” Journal of Petroleum Technology 25.07 (1973): 860-870.

William D. McCain. The properties of petroleum fluids. PennWell Books, 1990.