Ensaios tipo slug pneumáticos em furos de grande diâmetro

Abstract

There is a need for an alternative method to conventional pumping tests that is logistically easier and faster to use and which can be handled by only one person. The well known slug test fulfils those requirements if the equipment is properly designed. The applicability of small-diameter slug-test equipment using pneumatic initiation in large-diameter wells, up to 12aEuro(3) (0.3 m), is discussed. In wells with 36 times greater cross-sectional area than the slug-test equipment, it will take a long time for casing depressurization after slug initiation. The casing-depressurization time was measured for each slug test and is presented as a part of the results. The small-diameter equipment was found to be applicable and the long casing-depressurization times did not generally affect the transmissivity estimates. The series of slug tests yielded transmissivity estimates that were in good agreement with each other and also when compared with estimates from pumping tests. However, the slug-test results from wells completed in more permeable formations were harder to interpret, and may be an effect of long casing-depressurization times; further investigations are needed. There is a description of the design of several airtight couplings between the slug-test equipment and the casing. (Less)