STUDY ON THE EFFECT OF VACUUM ON RESTARTING THE PUMP OF GOLD CRUDE OIL IN PRODUCTION PIPELINE. Waxy crude oil can be found in many parts of the world for exploration and production purposes.
- Background Study
- Problem Statement
- Objectives
- Scope of Study
The problem of restarting the flow of the gelled crude oil in the pipeline will therefore be the main problem. The study of the compressibility of the gelled crude oil and the effect of gas voids would provide a better prediction of the restart pressure.
Theory
The same function as WAT, the pour temperature is the limiting temperature at which the gel structure is formed from crude oil (Venkatessan et al., 2002). Without any stress, this is also known as the gelation temperature as it is the temperature at which the gel forms.
Literature Review
The difference stage of crude oil upon reaching the WAT point can be seen in Figure 2.2. The red area shows the high temperature from the reservoir, while the blue part shows the extreme temperature drops in the pipeline, which eventually results in the formation of waxy gelled crude oil. When the pipeline temperature drops below the pour point temperature, the unfit wax crude undergoes thermal contraction.
Example of the DEHS system where it is installed in North Sea lines is shown in Figure 2.5 (Lenes et al., 2005). The pigs will run through the pipeline to scrape off the wax and gel that has deposited on the inner wall of the pipeline. The two main categories of the inhibitor are thermodynamic hydrate inhibitor (THI) and low dose hydrate inhibitor (LDHI) (Paez et al., 2001).
This will avoid more accumulation of the wax particles that can clog and block the pipeline. Furthermore, the proper study of the properties of the learned crude oil is important to reduce the Capital Expenditure Costs (CAPEX Costs) and ensure a constant flow of crude oil (Borghi et al., 2003). This proves that the formation of gas voids actually affects the compressibility of the educated crude oil, which can reduce the restart pressure of the operation.
The yield stress of the gel can be extremely high and exceed the maximum allowable pressure that the pipe can carry Nguyen et al., 2001 As the microstructure of the crude oil is affected by. The journal shows the experiment using different types of waxy crude oil with different approaches to the model.
Project Planning
- The overview of the project flow
- Understanding the Working rig
- Gantt Chart
Test the compressibility factor of gelled crude oil using the pneumatic system concept. Have knowledge of the setup, which is the old rig and used materials such as crude oil, preparation of the seabed condition, pipes of PVC and arcylic and sheet metal of the crude oil. Perform the wax appearance temperature (WAT) and pour point temperature (PPT) experiments and analyze the result.
Run of flow loop using the design pipe to test the voids affecting the crude oil re-pressurization. Since the project involves the tool, some knowledge about how the tool worked is very essential. From here it is important to identify the basic information and principle of the project.
For example, get to know the property of the fluid and the working principle of the old and new rig. The flow in Figure 3.2 shows the main idea of how the experiment was actually conducted. However, in the third phase, where the test section is in seabed condition, the experiment will be conducted with and without air injection to find out the effect of the formation of voids.
Wax Appearance Temperature (WAT) and Pour Point Determination
The sample was heated without stirring to 9°C above the expected pour point, but to at least 45°C, in a bath maintained at 12°C above the expected pour point, but at least 48°C. Test flask was placed in water bath maintained at 24°C and the pour point temperature was observed. The appearance of the sample was observed when the temperature of the sample is 9°C above the expected pour point (estimated as a multiple of 3°C).
At each test thermometer reading that is a multiple of 3°C below the starting temperature, remove the test vial from the jacket. Tilt the flask just enough to determine if there is any movement of the sample in the test flask. Once the sample in the flask does not flow when tilted, hold the flask in a horizontal position for 5 s, as indicated by an accurate timing device and observe carefully.
If the sample shows any movement, immediately place the test jar back in the jacket and repeat the flow test at the next temperature, 3°C lower. Continue in this manner until a point is reached where the sample shows no movement when the test jar is held in a horizontal position for 5 seconds. The observed reading of the test thermometer was recorded and used for the analysis of the study.
The rig and pipe design
The crude oil is left running in a constant heating and cooling mode until the crude oil in the test section gelled. The experiment will be performed with and without air injection to compare the effect of void appearance with the compressibility of the crude oil. The archyl tube from Figures 3.8 and 3.9 was used to facilitate the observation and measurement of the length after the crude oil has gelatinized.
Valve was used to open or close the piping section when needed. d) The refrigerator. In this setup, the ice is inside the box to maintain the cold temperature of the test area, similar to the temperature of the sea floor. e). First, the crude oil was heated to a certain temperature and then left in the flow loop until the crude oil in the test section was full.
After some times, when the crude oil gelled up, the formation of cavities will be observed in the test section. The time it takes for the crude oil to gel will roughly take about 1 hour to 1 hour and 30 minutes. The cycle pump is connected to the pressure gauge, and the end pipe is connected to the pipe to push the pipe to compress the gelled crude oil.
- Wax Appearance Temperature (WAT) analysis
- Pour Point Temperature Analysis
- The data analysis of Effect of Gas Voids Formation in Gelled Crude Oil
- The compressibility calculation
Based on the data in Table 4.3 and Table 4.4, a graph was created to identify the trend of the experiment. The constraints that need to be solved are the leakage of the piston system and the ways to quantify the force needed to apply to the crude oil. Based on Figure 4.3, it appears that the applied force will affect the length of the crude oil.
The components involved in equation 4.1 are; c for the compressibility factor, V is the volume of the fluid, P is the pressure on the fluid, and p is the density of the fluid used. The constant variable used for the data in Table 4.5 is the volume of the liquid, which is equal to 0.0012 m3, the pressure on the liquid is 0.5 bar, which is equal to 50 kN/man, the density of the liquid is 847 kg/m3 . The constant variable used for the data in Table 4.6 is the volume of the liquid, which is equal to 0.0012 m3, the pressure on the liquid is 1 bar, which is equal to 100 kN/man, the density of the liquid is 847 kg/m3.
The pressure of 0.5 bar may not affect the compressibility of gelled crude that much. However, since there are small differences, the pressure and condition of the sample still affect the compressibility. In Figure 4.5, the bar graph shows the comparison of sample 1 with the original condition and sample 2 when air is injected into the crude oil.
Conclusions
The result of the compressibility factor based on the data, which is at 0.5 bar, the compressibility factor for sample 1 is 0.001, while for sample 2 it is 0.003. It is tested using different pressures to show how much the pressure can compress the gelled crude oil. With this, the compressibility factor can then be incorporated into the equation to calculate the restart pressure.
This factor was the result of changes in gas voids and thermal shrinkage created by the crude oil gel. However, the limitation to perform the compressibility factor and the design should be overcome and improved for better and meaningful results in the future.
Recommendations
2003) “Prediction and Scaleup of Waxy Oil Restart Behavior,” paper presented at the SPE International Symposium on Oilfiled Chemistry, Houston, Texas, February 5-8. Non-Equilibrium Models", paper presented at the SPE Annual Technical Conference and Exhibition, Denver, Colorado, October 5-8, 2008) "Pressure Effect on Waxy Crude Pipeline-Restart Condition Investigated by a Model System", paper presented at the annual technical conference of SPE Conference and Exhibition, Denver, Colorado, November 21-24.
Crude Oil Restart:Mechanical Properties of Gelled Oil", paper presented at SPE Annual Technical Conference and Exhibiton, Houston, Texas, October 3-6. 34; Longer and Colder: Wax Control for Long Step-Out Distances", paper presented at IEEE 2012 Services Workshop on Security and Privacy Engineering, Honolulu, Hawaii, USA, 24-29 June 2012. Journal of Engineering and Applied Sciences, 7 (4), pp Measurement of Waxy Crude Properties Using Novel Laboratory Techniques", paper presented at 2000 SPE Annual Technical Conference and Exposition, Dallas, Texas, October 1-4, 2000.
34;Hydrate prevention on long pipelines by direct electric heating", paper presented at the Proceedings of the Eleventh International Conference on Offshore and Polar Sea Engineering, Seoul, Korea, June 19-24. Effect of Thermal History on the Wax Structure of Statically Cooled Wax Crude of Oil. Practical Guidelines for Field Rehabilitation", paper presented at the Petroleum Engineering Conference of Latin America and the Caribbean, Buenos Aires, Argentina, March 25-28, 2001. 34; Ensuring flow: Validation of wax deposition models using field data from a subsea pipeline", paper presented at the Offshore Technology Conference, Houston, TX, USA, 2-5 May 2011.
