Production Optimization, A Surface Roughness Approach
F.F. Farshad, H.H. Rieke (UL at Lafayette), D.Barbin (Chevron-Texico), and C. Briley (Tuboscope, Inc.)
Abstract
The acceptance of surface engineering technology to mitigate internal pipe surface roughness is becoming a strong economic component in the application of Gulf Coast operator flow assurance programs. Flow rates were increased up to 22% in recent Gulf of Mexico field tests. Three case histories are presented.
Today the use of oil country tubular goods (OCTG) mandates a reduction in the friction pressure losses and an increase in the power of mechanical components. This is
especially true when developing deep-water production with the expectation of maximizing the return on investment. The prediction performance, production optimization, and productivity of a gas or oil well are strongly affected by surface
roughness of the tubing production string. Indeed, this aspect has received scant attention in the literature. Surface roughness mitigation depends on different technological
competencies including tribology, material science, and mechanical engineering.
However, the foundation of the surface roughness minimization process is based on the ease of measuring how rough a surface is and how these measurements fit into a flow assurance strategy of greatly improving the flow of fluids in tubing strings and flow lines.
The use of internally coated pipes in the oil field started in the early 1940’s, when our industry first came concerned with corrosion in gas condensate wells. Tribological internally plastic coatings are used to extend the life of pipe by abating the interactions of produced corrosive fluids with metal. Presently, there are various different classes of coatings available to extend the life of OCTG. In addition to forming a protective
physical barrier against wear and corrosion, new internal coatings have been developed to achieve important pipe flow efficiencies. Case histories of recent field-test results show that internal coating mitigation approach to surface roughness in Gulf Coast production systems optimized rate recovery efforts.
Introduction
The petroleum industry during the past 20 years has experienced rapid development and integration of important new and creative technologies. Major applications such as time- lapse seismic, horizontal wells, corrosion resistant pipe coatings and alloys
,4,5,6, and computer utilization
,7,8,9not only made exploration, production, transportation, and refining performance more efficient, but has added significant cost reduction benefits to their operations.
Currently, one area of industry’s focus is on achieving infrastructure cost reductions in
the transport of gas and oil through pipelines. Surface roughness
10,11,12technology of
piping is good example of one such application. This is a major step forward in design,
which lowers the cost of pressure loss associate with fluid flow and by helping to extend the life of commercial piping. Pipe internal surface roughness impedes the dynamic transfer of fluids and is a problem in the optimization of production tubing and pipeline utilization along with corrosion.
As depth increases, so do reservoir pressure and temperature and the mole fraction of carbon dioxide and hydrogen sulfide in the reservoir gas. Furthermore, it is becoming more and more desirable for the operators to produce gas at high flow rates. These factors result in an increase in the corrosiveness of produced fluids and the percentage of wells with corrosion problems.
The seriousness of oil-field corrosion problems has long been recognized by the
petroleum industry. Industry began using internal coated oil field tubular goods in 1943, when the industry first became concerned with this problem and began to apply internal coatings to pipe. A coating is considered to be any thin material, which is firmly attached to the base metal wall and has the function of providing a barrier between the metal and the environment. Internal coatings such as phenolic thermoset polymer, epoxy, nylon, are used to extend the life of the pipe by mitigating any interaction with corrosive fluids.
Initially the coating technology was not perfect and resulted in holidays and build-ups during its application to internal and external surfaces of pipes. Current coating
technology has a much better record in eliminating holidays that create sites for corrosion and impede fluid flow. Despite its practical relevance, until now little work has been published on the measured surface roughness of coated pipes
13,14,15. Indeed, this aspect has received scant attention in the piping literature. Research by the piping industry is focus on improving the smoothness of internal pipe walls. It should be noted that research results from physical measurements
16,17, mathematical modeling studies, and statistical analysis of surface roughness in coated pipes are still scarce in the engineering literature.
Surface Roughness
A transition from “smooth” to a “rough” surface varies with the thickness of the laminar fluid layer, which is governed by certain flow properties. Therefore pipe surfaces can behave as a “smooth” or “rough” surface depending upon the magnitude of the Reynolds number. A “smooth” pipe surface is defined when the surface projections are completely submerged in the viscous laminar layer (thickness could be a few molecules thick) so that the internal pipe texture has no effect on the turbulent mixing of the fluid. When the height of the projections approach or exceed the thickness of the viscous sublayer, the projections serve to increase the fluid’s turbulence. At relatively high fluid velocities in pipe, surface roughness becomes increasingly important factor affecting turbulence and friction pressure loss.
Still many engineers in the petroleum industry determine an estimated friction factor value for a pipe from Moody’s relative pipe roughness chart (Fig. 1).
Calculation of the frictional pressure drop in piping requires determining values for the
friction factor, which is based on the surface roughness of the pipe. Moody in 1944
published his classical friction factor chart based on the analysis of Pigott’s 10,000
laboratory flow results in 1933, and the experiments using artificially sand-grain
roughened pipe walls by Nikuradse in Germany. The friction factor chart is a practical
solution to the Colebrook-White equation. The Colebrook-White equation is the
accepted standard used to calculate the friction factor owing to its demonstrated
applicability over a very wide range of Reynolds numbers and relative roughness values.
Moody’s chart has not been updated to consider the relative roughness for Cr 13, internally coated, and other newly developed pipes. The application of internally coated pipe technology was just being established for field use in the early mid 1940s.
Additionally, Moody did not use regression analysis of the data to generate equations, which related the relative roughness, /D, as a function of the internal pipe diameter, D.
Need to include a paragraph about our own surface roughness papers and relative roughness charts and equations developed.
Coatings
Any thin material, which is firmly attached to the base metal and has the function of providing a barrier between the metal and the environment, can be referred to as a coating. They can be used to enhance appearance, prevent product contamination,
increase flow capacity, and reduce corrosion. The coatings range from thin films of paint with a thickness of 5 to 8 mils, to heavy coal tar epoxy, which has a thickness of greater than 100 mils. Applications range from galvanized coatings for atmospheric protection, external pipeline coatings to reduce cathodic protection requirements, to internal
production coatings, which can reduce corrosion inhibitor requirements. The number of possible applications is limitless and the type of coating selected will be dictated by the economics of the situation.
Internal Coatings. Many organic compounds have been used to minimize corrosion
11, 12. In pipes, thermoset coating materials are normally deposited at between 5 and 15 mils in thickness. The thickness of thermoplastic coating materials is normally between 10 and 25 mils. These various types of coatings are discussed below:
Phenolic. Phenolic is a type of thermoset polymer and provides general chemical resistance to a temperature of 400 F. They are mostly based on phenol formaldehyde.
The best-known example is bakelite. This type of polymer has less flexibility than epoxies, but exhibit higher chemical resistance. They are unaffected by salt brine containing CO
2or oxygen, and can withstand the hydrochloric and hydrofluoric acids used in oil field acidizing operations.
Epoxy. Epoxies such as durcon, epon, and araldite, provide general chemical resistance to 175F and they have excellent flexibility in thick films (10 – 15 mils).
Modified Epoxy-Phenolic. This material provides both general chemical resistances to 250F and good flexibility in thin films (5-9 mils)
Modified Urethane. It provides both general resistance to 225 F and excellent flexibility in thick films (5 - 9 mils).
Nylon. It provides corrosion resistance in CO
2, water, and hydrocarbon environments up to 225F and protects the pipe from the corrosive material flowing through it.
Production Optimization
Oil and gas produced form the wells located in the Gulf coast region of Louisiana provides a large portion of the nation’s future energy. Therefore, the prediction of the long-term deliverability of such wells is of great importance. The prediction of the decline of average field pressure during the producing life of a reservoir and accurate calculations of pressure losses in the producing system are essential in order that reservoirs may be produced efficiently and economically. In the completion and operation of a reservoir a given deliverability must be maintained with transfer at a certain pressure at the sales point. The engineer is often faced with the decision of how to select and size the producing equipment necessary to maintain deliverability as the reservoir pressure declines. In the cases where the wells have already been completed, it may require larger tubing strings or smoother tubing. Obviously, the optimal combination of the various factors is necessary in order to acquire the maximum economic return from the producing property.
There are numerous wells in the Gulf Coast area as well as around the world that have not been totally optimized and are producing far below their optimum and efficient flow rate. In fact, in many cases, the wells are completed in a manner that their optimum and efficient rate cannot be achieved.
The production system is usually composed of three distinct elements. The 3 elements of the system can be characterized as follows:
1. Flow through the reservoir with the pressure drop from the average reservoir pressure to the sand-face flowing pressure. This segment consists of the flow through the porous media.
2. Flow through the well completion section with the pressure drop from the sand-face flowing pressure to the bottom-hole flowing pressure. This segment consists of fluid flow through the perforation tunnels. Perforation tunnels can be gravel-filled or conventionally perforated tunnels that are not gravel-packed.
3. Flow through the producing string of the well with the pressure drop from the bottom- hole flowing pressure to the wellhead flowing pressure. This segment consists of fluid flow in vertical or directionally drilled (deviated) wells.
Well deliverability and, consequently, total optimization of the production system, can
be calculated when all the above components are considered simultaneously. The
components of the system must be integrated in such a manner that pressures balance at
each point in the system. At the same time, flow rates must be consistent with calculated
reservoir and flowing bottom-hole pressures. Any approach to the aforementioned design
studies that does not consider all production system components cannot properly account
for all the interacting influences on system deliverability. The deliverability and
optimum flow rate for a well can be determined in two ways, mathematically
*and
graphically. Both procedures require first selecting a division point (node) and
calculating the division point pressure, starting at the fixed or constant pressures existing
in the system. These fixed pressures are normally the average reservoir pressure and the delivery pressure.
In the mathematical approach
*, flowing pressures are calculated at every division point in the system. This is done by an iterative technique that integrates the different system components. With a suitable mathematical model, a rate and a wellhead pressure are assigned for the production system, and the flowing bottom-hole pressure is calculated in two ways, from the piping side and from the reservoir side. The iterative process is continued until an optimum value of flow rate is obtained. The graphical technique was first presented by Gilbert
2. The graphical technique known as total optimization of production system (TOPS), production optimization, system analysis, and Nodal analysis have already been presented in details elsewhere and will only be summarized here
The concept requires preparation of pressure-flow diagrams combining the well inflow performance relationship (IPR) with the tubing (equipment) intake curve, which is the pressure loss in the tubing producing string. The IPR curve represents a particular state of depletion or external reservoir pressure and the intake curve represents a particular tubing diameter. These curves illustrate that, as bottom-hole pressure increases, flow rate from the reservoir will decrease while flow rate through the tubing string will increase.
Hence, at high bottom-hole flowing pressures, the flow rate of a well may be limited by the roughness or the size of the pipe.
Farshad, F., T. C. Pesacreta, J. D. Garber, S. R. Bikki, “A Comparison of Surface Roughness of Pipes as Measured by Two Profilometers and Atomic Force Microscopy”, Scanning, Vol. 23, (2001) p. 241-248.
Farshad, F., H. Rieke, J.D. Garber, “New Developments in Surface Roughness Measurements, Characterization, and Modeling Fluid Flow in Pipe”, Journal of Petroleum Science & Engineering, 29 (2001) p. 139-150.
Farshad, F., J.D. Garber, and V. Polaki, “Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2", SPE Prod. & Facilities Journal, 15(3), August 2000.
Farshad, F., J.D. Garber, and J. Lorde, “Predicting Temperature Profiles in Producing Oil Wells Using Artificial Neural Networks”, Engineering Computations, Vol. 17 No. 6, 2000, pp. 735-754.
Farshad, F., Sheng, Qin, and Duan, Shangyu, "A Simulation of Crystallinity Gradients Developed in Slowly Crystallizing Injection Molded Polymers Via Parallel Splitting," Engineering Computations, Vol.
16, Nov. 8, 1999, p. 892-911.
Petrosky, G.E. and F. Farshad, “Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils,” SPE Reservoir Evaluation and Engineering Journal, October 1998.
Proceedings:
Farshad, F., H. H. Rieke, C. Mauldin, “Flow Test Validation of Direct Measurement Methods Used to Determine Surface Roughness in Pipes (OCTG)”, SPE 76768, Proceedings of the SPE Western Regional/AAPG Pacific Section Joint Meeting, Anchorage, Alaska, May 2002.
Farshad, F., J. Linsley, O. Kuznetsov, and S. Vargas, “The Effects of Magnetic Treatment on Calcium Sulfate Scale Formation”, SPE 76767, Proceedings of the SPE Western Regional/AAPG Pacific Section Joint Meeting, Anchorage, Alaska, May 2002.
Farshad, F., J.D. Garber, J. Linsley, “New Developments in Surface Roughness of Chrome 13 pipes (OCTG), A Direct Measurements-Characterization Approach”, SPE 67245, Proceedings of the SPE Production and Operations Symposium, Oklahoma City, Oklahoma, March 2001.
Farshad, F., J.D. Garber, and J.R. Reinhardt, “A Model For Predicting Corrosion Rates in Oil Wells Containing Carbon Dioxide”, SPE 66651, Proceedings of the SPE/EPA/DOE Exploration and Production Environmental Conference, San Antonio, Texas, February 2001.
Farshad, F., “New Developments in Surface Roughness Measurements-Characterization of Chrome 13 Pipes (OCTG)”, Proceedings of 1st International Conference on Advanced Materials Processing, Rotorua, New Zealand, Nov. 19-23, 2000.
Farshad, F. and J.D. Garber, “Relative Roughness Chart for Internally Coated Pipes (OCTG),” SPE 56587, Proceedings of the 1999 SPE Annual Technical Conference and Exhibition, Houston, TX, October 3-6, 1999.
Farshad, F., T.C. Pesacreta, S.R. Bikki, and R.H. Davis, “Surface Roughness in Internally Coated Pipes (OCTG), OTC 11059, Proceedings of the 1999 Offshore Technology Conference, Houston, TX, May 3-6, 1999.
Farshad, F, J.D. Garber, and J.N. Lorde, “Prediction of Temperature Profiles in Oil & Gas Wells Using Neural Network Model,” SPE 53738, Proceedings of the SPE 6th Latin American and Caribbean Petroleum Engineering Conference, Caracas, Venezuela, April 21-23, 1999.
Farshad, F., J.D. Garber, V. Polaki, “A Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2,” SPE 40003, Proceedings of the 1998 SPE Gas Technology Symposium, 15-18 March 1998, Calgary, Alberta, Canada.
Farshad, F., J.L. LeBlanc, J.D. Garber and J.G. Osorio, “Emperical PVT Correlations for Colombian Crude Oils,” SPE Paper 36105, Proceedings of the Fourth Latin American and Caribbean Petroleum Engineering Conference, 23-26 April 1996, Trinidad and Tobago.
Petrosky, G.E. and F. Farshad, “Viscosity Correlations for Gulf of Mexico Crude Oils,” SPE Paper 29468, Proceedings of the Production Operations Symposium, 2-4 April 1995, Oklahoma City, OK.
1. Farshad, F., Pesacreta, T., Garber, J., Bikki, S., " A Comparison of Surface Roughness of Pipes as Measured by Two Profilometers and Atomic Force Microscopy", The Journal of Scanning Microscopies, 23 (2001) P. 241-248.
2. Farshad, F., H. Rieke, J.D. Garber, “New Developments in Surface Roughness Measurements, Characterization, and Modeling Fluid Flow in Pipe”, Journal of Petroleum Science &
Engineering, 29 (2001) p. 139-150.
3. Farshad, F., J.D. Garber, and V. Polaki, “Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2", SPE Prod. & Facilities Journal, 15(3), August 2000.
4. Farshad, F.,Sheng, Qin, and Duan, Shangyu, "A Stimulation of Crystallinity Gradients Developed in Slowly Crystallizing Injection Molded Polymers Via Parallel Splitting,"
International Journal for Computer-Aided Engineering and Software, Vol. 16, Nov. 8, 1999, p.
892-911.
5. Farshad, F., J.D. Garber, and J. Lorde, “Predicting Temperature Profiles in Producing Oil Wells Using Artificial Neural Networks”, Engineering Computations, Vol 17 No. 6, 2000, pp 735- 754.
6. Petrosky, G.E. and F. Farshad, “Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils,” SPE Reservoir Evaluation and Engineering Journal, October 1998.
1. Farshad, F., Pesacreta, T., Garber, J., Bikki, S., " A Comparison of Surface Roughness of Pipes as Measured by Two Profilometers and Atomic Force Microscopy", The Journal of Scanning Microscopies, 23 (2001) P. 241-248.
2. Farshad, F., H. Rieke, J.D. Garber, “New Developments in Surface Roughness Measurements, Characterization, and Modeling Fluid Flow in Pipe”, Journal of Petroleum Science &
Engineering, 29 (2001) p. 139-150.
3. Farshad, F., J.D. Garber, and V. Polaki, “Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2", SPE Prod. & Facilities Journal, 15(3), August 2000.
4. Farshad, F.,Sheng, Qin, and Duan, Shangyu, "A Stimulation of Crystallinity Gradients Developed in Slowly Crystallizing Injection Molded Polymers Via Parallel Splitting,"
International Journal for Computer-Aided Engineering and Software, Vol. 16, Nov. 8, 1999, p.
892-911.
5. Farshad, F., J.D. Garber, and J. Lorde, “Predicting Temperature Profiles in Producing Oil Wells Using Artificial Neural Networks”, Engineering Computations, Vol 17 No. 6, 2000, pp 735- 754.
6. Petrosky, G.E. and F. Farshad, “Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils,” SPE Reservoir Evaluation and Engineering Journal, October 1998.
7. Petrosky, G.E. and F. Farshad, "Pressure-Volume-Temperature Correlations for Gulf of Mexico Crude Oils," SPE Reservoir Evaluation and Engineering Journal, October 1998.
8. Farshad, F. and J.L. LeBlanc, "Rewards/Challenges of Academic PE," Journal of Petroleum Technology, December 1994.
9. Farshad, F. and J.L. LeBlanc, "How to Run A Fortran or a Basic Computer Program on PC's, SPE Computer Applications Magazine, May-June 1990 issue.
10. Sutton, Robert P. and F. Farshad, "Evaluation of Empirically Derived PVT Properties for Gulf of Mexico Crude Oils," SPE Reservoir Engineering Journal, Feb. 1990.
11. Farshad, F. and J.D. Garber, "How to Increase Gas Well Production and Temper Corrosion,"
Part I, April 1983, The Journal of Petroleum Engineering International.
12. Farshad, F. and J.D. Garber, "How to Increase Gas Well Production and Temper Corrosion,"Part II, May 1983, The Journal of Petroleum Engineering International.
13. Farshad, F. and J.D. Garber, "How to Increase Gas Well Production and Temper Corrosion,"
Part III, June 1983, The Journal of Petroleum Engineering International.
14. Stelly II, O.V. and F. Farshad, "Predicting Gas In Place in Abnormally-Pressured Reservoirs,"
June 1981, The Journal of Petroleum Engineering International.
15. Arnondin, M., M. van Poollen and F. Farshad, "Predicting Bottomhole Pressure for Gas and Gas Condensate Wells," November 1980, The Journal of Petroleum Engineering International.
1. Farshad, F., J.D. Garber, J. Linsley, “New Developments in Surface Roughness of Chrome 13 pipes (OCTG), A Direct Mearsurements-Characterization Approach”, SPE 67245, Proceedings of the SPE Production and Operations Symposium, Oklahoma City, Oklahoma, March 2001.
2. Farshad, F., J.D. Garber, and J.R. Reinhardt, “A Model For Predicting Corrosion Rates in Oil Wells Containing Carbon Dioxide”, SPE 66651, Proceedings of the SPE/EPA/DOE Exploration and Production Environmental Conference, San Antonio, Texas, February 2001.
3. Farshad, F. and J.D. Garber, “Relative Roughness Chart for Internally Coated Pipes (OCTG),”
SPE 56587, Proceedings of the 1999 SPE Annual Technical Conference and Exhibition, Houston, TX, October 3-6, 1999.
4. Farshad, F., T.C. pesacreta, S.R. Bikki, and R.H. Davis, “Surface Roughness in Internally Coated Pipes (OCTG), OTC 11059, Proceedings of the 1999 Offshore Technology Conference, Houston, TX , May 3-6, 1999.
5. Farshad, F, J.D. Garber, and J.N. Lorde, “Prediction of Temperature Profiles in Oil & Gas Wells Using Neural Network Model,” SPE 53738, Proceedings of the SPE 6th Latin American and Caribbean Petroleum Engineering Conference, Caracas, Venezuela, April 21-23, 1999.
6. Farshad, F., J.D. Garber, V. Polaki, “A Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2,” SPE 40003, Proceedings of the 1998 SPE Gas Technology Symposium, 15-18 March 1998, Calgary, Alberta, Canada.
7. Farshad, F., J.L. LeBlanc, J.D. Garber and J.G. Osorio, “Emperical PVT Correlations for Colombian Crude Oils,” SPE Paper 36105, Proceedings of the Fourth Latin American and Caribbean Petroleum Engineering Conference, 23-26 April 1996, Trinidad and Tobago.
8. Petrosky, G.E. and F. Farshad, “Viscosity Correlations for Gulf of Mexico Crude Oils,” SPE Paper 29468, Proceedings of the Production Operations Symposium, 2-4 April 1995, Oklahoma City, OK.
9. Farshad, F., T.C. Pesacreta, S.R. Bikki, and R.H. Davis, "Surface Roughness in Internally Coated Pipes (OCTG),OTC 11059, Proceedings of the 1999 Offshore Technology Conference, Houston, TX, May 3-6, 1999.
10. Farshad, F. J.D. Garber, and J.N. Lorde, "Prediction of Temperature Profiles in Oil & Gas Wells Using Neural Network Model," SPE 53738, Proceedings of the SPE 6th Latin American and Caribbean Petroleum Engineering Conference, Caracas, Venezuela, April 21-23, 1999.
11. Farshad, F., J.D. Garber, V. Polaki, "A Comprehensive Model for Predicting Corrosion Rates in Gas Wells Containing CO2," SPE 40003, Proceedings of the 1998 SPE Gas Technology Symposium, 15-18 March 1998, Calgary, Alberta, Canada.
12. Farshad, F., J.L. LeBlanc, J.D. Garber and J.G. Osorio, "Empirical PVT Correlations for Colombian Crude Oils," SPE Paper 36105, Proceedings of the Fourth Latin American and Caribbean Petroleum Engineering Conference, 23-26 April 1996, Trinidad and Tobago.
13. Petrosky, G.E. and F. Farshad, "Viscosity Correlations for Gulf of Mexico Crude Oils," SPE Paper 29468, Proceedings of the Production Operations Symposium, 2-4 April 1995, Oklahoma City, OK.
14. Farshad, F., J.L. LeBlanc and P.J. Root, "A Predictive Model Enhances Optimized Production and the Completion of the Production System," SPE Paper 28763, Proceedings of the Asia Pacific Oil & Gas Conference, 7-10 November 1994, Melbourne, Australia.
15. Petrosky, G.E. and F. Farshad, "Pressure-Volume-Temperature Correlation for Gulf of Mexico Crude Oils," SPE Paper 26644, Proceedings of the 68th Annual Technical Conference and Exhibition of the SPE, 3-6 October 1993, Houston, TX.
16. Alvarado, G., J.L. LeBlanc and F. Farshad, "A New and Improved Material Balance Equation for Retrograde Gas Condensate Reservoirs - Part I," SPE Paper 24355, Proceedings of the SPE Rocky Mountain Regional Meeting, 18-21 May 1992, Casper, WY.
17. Farshad, F., J.L. LeBlanc and P.J. Root, "A Predictive Model for Analyzing Erosional Velocity and Corrosion Effects Enhances Optimized Production of a Gas Well System", SPE Paper 17719, Proceedings of the SPE Gas Technology Symposium, 13-15 June 1988, Dallas, TX.
18. Sutton, Robert P. and F. Farshad, "Evaluation of Empirically Derived PVT Properties of Gulf of Mexico Crude Oil," SPE Paper 13172, Proceedings of the 1984 Fall Meeting, Society of Petroleum Engineers, 16-19 September 1984, Houston, TX.
19. Toh, C.H., F. Farshad and J.L. LeBlanc, "A New Iterative Technique with Updated Curves for Estimating Average Reservoir Pressure of Gas Wells from Buildup Test," SPE Paper 13235, Proceedings of the 1984 Fall Meeting, 16-19 September 1984, Houston, TX.
20. Sutton, R.P. and F. Farshad, "Utilization of Peng-Robinson Equation of State in Multi-phase Flow Pressure Gradient Calculation," SPE Paper 11884, Proceedings of the 1983 European Offshore Technology Conference, Aberdeen, Scotland.Accepted for JPT publication.
21. Ramagost, Billy P. and F. Farshad, "P/Z in Abnormally-Pressured Gas Reservoirs," SPE Paper 10125, Proceedings of the 1981 Fall Meeting, Society of Petroleum Engineers, 5-7 October 1981, San Antonio, TX.Accepted for JPT publication.
22. Revett, L., B. Ayeni, F. Farshad and A. Hayatdavoudi, "Using Petrophysical Data to Differentiate a Separate Water Bearing Zone from a Water Level," SPE Paper 10066, Proceedings of the 1981 SPE National Convention, 5-7 October 1981, San Antonio, TX.
23. Fang, C.S., J.D. Garber, F. Farshad and R.C. Broadhurst, Jr., "Recovery of Heat and Carbon Dioxide from Compressor Station Exhaust Gas," SPE Paper 9914,
