Flow Test of a Perforated Deep Dual Cased Well

Abstract

An example of well testing when there are limitations in available fluid storage capacity reducing the testing time. Flow tests were carried out in a deep geothermal well in the southernmost province of Sweden. The well is 3701.8 m deep with production zones located in a low temperature reservoir consisting of Cretaceous sandstone. The potential production zones were cased with dual casing, which was cemented into position. Perforation was used to reopen the production zones between 1425 m and 1950 m, followed by airlifting to clean out the debris. The production zones were flow tested separately as well as combined. The hydraulic parameters are evaluated applying groundwater well tests equations. One problem during the flow tests was the limited storage capacity at the drillsite, which affected the testing time. Because of this limitation no hydraulic boundaries were reached during the flow tests. Injection took place after running out of storage capacity and the water was injected back into the sandstone formation. To treat the geothermal water in the municipal wastewater plant was a too expensive option, because of the high salinity of the water. Direct disposal was prohibited due environmental restrictions.