# Estimating Well Cost for Enhanced Geo System Applications

## Quiz Questions

 1. Which one of the following plays a role in enhanced geothermal systems (EGS) reservoir performance. Reservoir Geologic Drilling Well completion Plant design Operation All of the above 2. According to table 1. the drilling costs for a well with an average depth of 679 ft is: \$100 K \$280 K \$340K 3. According to table 1. the drilling cost for 5 wells with average depth of 4307 ft is : \$12,333 K \$10,857 K \$ 9,876 K 4. The average cost of per foot for a horizontal well was 17% higher than a well not drilled horizontally. Horizontal drilling averaged \$254/ft verses \$217/ft for a standard hole. True False 5. The objective of drilling is to reach the target depth or pay zone at the lowest cost, highest degree of safety, and minimal degree of damage to formation. To achieve this, two requirements must be satisfied. The first is proper design of the well program, which includes evaluating the formation, coring, and testing. The second is proper choice of a drilling rig, which includes the ability to reach the target depth rapidly and cheaply with the highest degree of safety. The well program is 40% of the well costs (Chilingarian and Vorabutr 1983). The remainder of the cost is proportional to the time for drilling, which includes rig day rate, rental tools, etc. True False 6. A distribution of the well program cost is: Fixed costs, which includes location or site preparation and roads: 8–12% Fixed costs, which includes moving, casing, cementing, service companies, evaluation of formation, coring, etc.: 23–27%Completion, which includes perforating and site cleanup: 4–6%. True False 7. The first step in planning a well is to gather all available data on past wells. It is important to be completely familiar with all sources of information, the availability of the sources, and the information normally associated with the sources. Consider the geology expected to be encountered to reach the target depth. Knowing the geology will help determine casing depths, such as the depth of fresh water. Competent geology will determine surface casing requirements. Understand the production objective of the well, such as hole size, production casing requirements, and completion requirements. Know the geologic markers, along with the anticipated formation tops, to determine other well planning activities such as logging, formation testing, and cores. True False 8. The information to successfully complete the well program can be obtained from an adjacent well or "control wells." Obtain such information as mud logs, electric logs, bit records as well as drilling rig inventory where available to determine the most cost-effective procedures in drilling a well. True False 9. On page 34 the total cost for the Roger Mills Co. in Oklahoma was: \$1,127,314 \$1,523,688 \$1,782,933 10. On page 30, the total completion cost for the Smith Co. in Texas is: \$873,000 \$734,000 \$534,000