Bir jeotermal rezervuarın birimleştirilmiş ve rekabetçi yararlanma koşulları altındaki performansı

Population growth and rising living standards remain as two of the key drivers for the increase of energy demand. Towards meeting such demand, as the technological advancements are crucial for diversifying energy sources, the adoptation of proper management strategies might be necessary for the efficient capacity development in existing sources. Geothermal energy, classified as a renewable energy resource is playing a vital role in this pursuit because the production system is able to sustain production levels over long periods. The longevity of production can be secured and sustainable production can be achieved, by using moderate withdrawal rates, while considering the local resource characteristics. A geothermal reservoir is indivisible by nature and so unregulated development of straddled leases overlying a reservoir, results in physical waste and under-utilization of resource, economic waste, environmental hazards, and inefficient resource management. The solution put forward to tackle this problem is unitization, which is defined as the voluntary or involuntary agreement by working interest owners of separate leases overlying the same reservoir to exploit and operate the resource as a cooperative and coordinated joint body under a designated operator. This concept delivers sustainable and efficient resource management, economic opportunities, and environmental benefits. The objective of this thesis concerns reservoir behaviour under production with time, where two leases of different reservoir temperatures are operated under competitive and cooperative development strategies, and coming out with the optimum development design to generate 20 MWe power. The study incorporates two stages. The first stage dwells on the comparison of reservoir behaviour under production with respect to time for competitive and cooperative utilization schemes. Reservoir pressure and reservoir temperature are the benchmarks for the analysis. The second stage is about the design of the appropriate development approach for a reservoir shared by two leases, assuming a constant electricity generation capacity throughout the project life. The lumped parameter modelling is an analytical technique used for projecting the pressure response of a geothermal system to extraction. Non-isothermal tank model is selected as the tool to account for significant temperature changes associated with marked differences between recharge temperature and reservoir temperature, variations resulting from injection operations, and decrease in reservoir temperature due to production of fluids. Three hypothetical cases of one-tank and two-tank models are proposed and analysed to study reservoir pressure and reservoir temperature behaviour relative to fluid production and time, with reinjection, under competitive and cooperative management of the two leases for constant electricity generation. The cases are set as, (a) Case 1: competitive approach with two leases, (b) Case 2: cooperative approach with unitized two leases, (c) Case 3: cooperative approach with unitized two leases (production in one lease and reinjection in other lease). The assumptions made in this study are, (i) arbitrarily chosen reservoir rock and fluid properties in both leases, (ii) constant electricity generation from binary power plants, (iii) a binary power plant with 10 MWe electricity generation capacity is installed on each competitive geothermal lease of different reservoir temperatures; or a binary power plant with 20 MWe electricity generation capacity is installed on the unitized leases, (iv) temperature of the recharge (aquifer) and its connected Lease 1 are equal at 180°C in all cases, (v) reservoir temperature in Lease 2 is 160°C, and (vi) project design life is limited to 10,000 days for all cases. The significance of this thesis is emphasized on selection of the most suitable development approach for a reservoir utilized by two straddled leases of different working interest owners. All the cases are evaluated in terms of the variation in average reservoir pressure, average reservoir temperature, net heat produced, and thermal efficiency of the power plant. Out of the three cases investigated the unitized approach, in which production is from Lease 1 and reinjection in Lease 2, is found to be the desired mode of operation to feed the 20 MWe capacity binary plant for the purpose of electricity generation. This case works best, because of well coordinated and informed technical decisions on appropriate well planning, based on extensive integrated data. Hot fluid zones are identified for production and are well separated from cooler regions, in which reinjection wells are to be located. The purpose of proper location of wells is to achieve the most efficient and sustainable energy production. As the reservoir section under Lease 1 is directly connected to the recharge source, from which the reinjection well is located far away in Lease 2, replenishment of produced fluids is at an adequate rate ensuring high average reservoir pressure. Locating the reinjection wells at a safe distance from the production wells in Lease 2, the temperature of the hot water zone is kept under control. Thus, the net heat produced would be very favourable, since the reinjected fluid is channelled through the reservoir section under Lease 2 to ensure minimal drop in temperature of the reservoir section under Lease 1, which enjoys hot liquid influx from the infinite size recharge source (aquifer). Case 3 also experiences the least drop in thermal efficiency of the binary power plant by the end of the design life. It can be concluded that the owners of straddled leases should be encouraged or imposed on to act in a cooperative strategy for an unitized management of land, geothermal energy, any heat or energy source surrounding the geothermal waters, and ecosystem to derive maximum benefits for all stakeholders and safeguard public interests.