Drilling Magazine Media Intelligence, Contextual Wisdom
Investigation and measurement of produced oil, gas and water from wells play an important role in reservoir management and production enhancement. Though the well testing is an essential and beneficial operation, achieving accurate data in appropriate period of time could be challenging due to some reasons.
The well testing operation is usually performed by means of test separators and other pressure control equipment which are transported to onshore or offshore operation site. For this well testing method which is based on gravity-based phase separation, the well production is ceased for some days while it is being prepared for well testing.
Though this is a tested and trusted method for well production test, it has some disadvantages due to the dependence of result accuracy to the complete or optimum segregation of produced phases. On the other hand, the outlet fluid from well may need some physical and chemical changes before entering the separator which needs application of several assistive and pressure control equipment.
In the cases where phase segregation has unfavorable quality or the separator has an unfavorable condition such as when the inlet fluid is foamy and carryover and carry under may take place, the measurement accuracy is extremely affected and the obtained data would not be reliable.
Risks of transportation of several heavy well testing equipment as well as occasional need for disassembling the main production pipeline and directing the flow to the well testing equipment and finally managing or burning the segregated fluids are other challenges of traditional method of well testing.
The costs related to the transportation, well testing operation and other necessary equipment as well as the cessation of production from the under test wells could limit the nominated wells for being tested. Consequently, the oil companies and owners would not achieve adequate information essential for field management which are gained by repeated well testing.
As an example, assuming that each production well must be tested two times a year and each test lasts three days considering the equipment installation time, test time and the time of removing the installations, an oil field with 100 production wells needs about 600 days for well testing operation to be accomplished. Performing this volume of operation needs the simultaneous application of several well testing units together with the engaged personnel which is not economically and operationally practicable in most of the cases.
Considering what mentioned above and other difficulties and limitations of common methods of well testing some novel methods should be investigated. One of these methods is the application of multi-phase flowmeters (MPFM). This technology was commercialized in 1994 and widely used in petroleum industry since 2000.
MPFM functions is based on passing total volume measurement and calculation of the percentage of each phase and finally each phase flowrate. Furthermore, it is not necessary to separate different phases of fluid to measure them.
MPFM becomes operational in shorter time and needs less accessories and assistive equipment in comparison to conventional test separators. It also needs less room to be installed which may be more important in offshore operations. Since the fluid phases are not separated in this method, the measured fluid could be again diverted to the production line.
Though this technology has been applied in world petroleum industry for years and is not mentioned as a novel technology now, it has not obtained its real value in our country. This is mainly due to the lack of owners’ interest in novel technologies and their tendency to use the tested methods.
MPFM is one of the technologies related to the well test services which was not welcomed by Iranian oil companies and there are far more technologies which their absence is felt in Iran oil industry. It is hoped that the new technologies will regain their place in Iran oil industry and oil companies pay more attention to the use of more efficient methods to save time, reduce costs and increase the production.
Davood Taheri
Senior Drilling Expert