Locating the producing layers in HGP-A

The characteristics of the Hawaii Geothermal Project well HGP-A were presented last year in terms of flow rates under throttled conditions, downhole pressure and temperature profiles, and pressure drawdown and buildup tests. In particular, the more recent pressure buildup analyses have indicated the possibility of multiple production zones. In an attempt to locate these production zones, two tests have been conducted during the past six months. A direct means of determining the locations of the permeable layers is to measure the flow rates at the suspected depths. However, two difficulties immediately arise. Since the flow in HGP-A is a mixture of saturated liquid and vapor, the mass flow rate cannot be measured using a conventional spinner (which is a volumetric flow meter). Furthermore, the temperature encountered in the wellbore exceed the temperature limits of that instrument. To circumvent both of these difficulties, the well was allowed to produce only under severely throttled conditions. This had the effect of keeping the well fluid in a liquid state at temperatures well within the capability of the flow meter. The flow meter setup used for the production and pumpdown tests is shown in Figure 1.. Authors: Kihara, D; Chen, B; Seki, A; Yuen, P. DOE Contract: NONE. Subjects: 02 PETROLEUM; 15 GEOTHERMAL ENERGY; BUILDUP; DRAWDOWN; FLOW RATE; GEOTHERMAL ENERGY; Geothermal Legacy; HAWAII; METERS; MIXTURES; MULTIPLE PRODUCTION; PRODUCTION; RESERVOIR ENGINEERING