Techbits: Key Reservoir-Testing Issues Examined by Workshop

Abstract

Techbits Eighty-seven participants, representing 48 organizations from 25 countries, attended the SPE Applied Technology Workshop (ATW) "Reservoir Testing in a World of High Production Values," held 11–14 December in Bali, Indonesia. The ATW comprised 11 sessions, including the keynote address by Tri Siwindono, chief executive officer, PT Pertamina. Siwindono focused on the value of information obtained in reservoir testing and noted that in the current environment of high production values, Pertamina rarely tests oil wells because of the cost of lost production. Most of his company's reservoir tests involve gas wells. He highlighted oil-producing countries' desire to find cost-effective and environmentally protective reservoir-testing methods. Session 2, chaired by Florian Hollaender, Schlumberger, and Bob Hite, Shell, dealt with new technologies and their applications. Henk Kool, Halliburton, made a presentation on a new bottomhole drillstem-test (DST) -conveyed sampling system. By use of this low-cost system, representative samples are captured under controlled timing and are overpressurized by means of a nitrogen cushion as they are carried to the surface, ensuring that the samples remain representative. Bertrand Theuveny, Schlumberger, discussed the current and possible future use of multiphase flowmeters (MPFMs). Of the more than 3,000 MPFMs currently deployed worldwide, including 150–200 mobile units, less than 400 are used regularly for well testing. MPFMs have yet to attain full acceptance by operating companies, Theuveny said. Challenges affecting the wider use of MPFMs, he indicated, include the economic limitations of metering low flow rates; bringing accurate multiphase-measurement technology downhole, as opposed to conducting metering at the surface only; making full use of the transient-rate information obtained from these meters; and data-reduction issues related to permanent meter installations or long-term tests. Ichiro Shikano, Nippon Oil, presented a case study in which a naturally fractured basement reservoir offshore Vietnam was characterized with a combination of pressure-transient tests with tracers. The reservoir-management objectives call for avoiding gas and/or water breakthrough. Water injection is used to manage the gas/oil and oil/water contacts, a challenge in the highly heterogeneous fractured configuration. To assess interwell communication, different tracers were introduced through injectors in different parts of the field, enabling a simple estimation to be made of the source of the water. Although the data-acquisition scheme did not resolve all uncertainties, the simulation model was updated on the basis of the interwell communication results, and a better history match was achieved.