Well flow testing in Sol de Mañana geothermal field in Bolivia,

Abstract

The Sol de Mañana geothermal field is located in Bolivia in the area of Potosí, Sud Lipez province. In the field 5 wells have already been drilled. The capacity of the field, based on information from existing wells and superficial studies, is estimated to be 100 MWe. Approximately 25 additional wells are to be drilled to produce this amount of energy. The first power plant will be installed as soon as energy, sufficient for 50 MWe is available at wellhead. Interference tests will be carried out to determine if there is any connection between the wells and to gain more information about the reservoir. Drilling of new wells and testing of the previously drilled wells will be carried out simultaneously. Caution will be exercised to minimize interference of the involved wells. When flow testing production wells, the Russel James method will be used to measure the well capacity. Orifice plates (Sizes 4, 6 and 8 inches in diameter) will be used to maintain the head pressure, the lip pressure will be measured in the lip pressure spool while the amount of brine produced will be measured in the weir box. The old wells will also be monitored for changes in pressure and static water level. Three wells are located on drilling pad 3; SM-3 (old), SM-31(new) and SM-32 (new). SM-31 will be the first well to be tested while wells SM-1, SM-2 and SM-3 are monitored for interference. Thereafter, the simultaneous testing will be started, whereby all the aforementioned wells will be opened using an 8 "orifice plate for a period of 5 days. Both the individual and simultaneous tests take approximately 40 days. The objective of the tests is to obtain the production capacity, the pressure and the temperature of the wells and to establish if interference exists between the wells. The test results together with geological studies can be used to revise the conceptual model of the reservoir.