降壓生產法應用於台灣西南海域天然氣水合物潛在礦區之生產效益

Efficiency of Depressurization Gas Production from Potential Hydrate Deposits Offshore Southwest Taiwan

10.30069/MM.201512_59(4).0003

吳政岳(C. Y. Wu)；楊嘉勝(J. S. Yang)；謝秉志(B. Z. Hsieh)

降壓生產法 ； 天然氣水合物 ； 油層模擬 ； 非傳統天然氣 ； Depressurization ； Gas Hydrate ； Reservoir Simulation ； Unconventional gas

鑛冶：中國鑛冶工程學會會刊

59卷4期（2015 / 12 / 01）

38 - 48

繁體中文

本研究的目的為利用數值模擬法模擬天然氣水合物於第一型天然氣水合物儲藏層之生產情況並評估台灣西南海域潛在天然氣水合物儲藏層利用降壓生產法的生產效益。研究所使用的數值模擬軟體，經由美國國家能源科技實驗室驗證，能精確的模擬天然氣水合物的生成與熔解。本研究以台灣西南海域的K 礦區作為研究標的，設定不同的生產策略，包含固定井底壓力（定壓降生產）及固定產率生產，兩種不同的生產操作條來模擬評估水合物礦區的開採效益。研究結果顯示，在定壓降生產的條件下，單井的採收率(RF) 為12.44%，其中自由氣層的採收率(RF_f) 為31.35% 水合物的採收率(RF_h) 為7.45%。由結果中所觀察到的水合物熔化後產生的水會於地層底部累積，此現象會使底部的天然氣產生向上推移效應，因此在第一型水合物儲藏層中，若在氣層頂部進行穿孔可避免多餘的地層水產出。

The purpose of this study was to use numerical simulation to estimate the gas production from a class-1 gas hydrate and to investigate the efficiency of depressurization gas production from a potential hydrate deposit located offshore southwestern Taiwan. The simulator used was validated in the code-comparison project supported by the US National Energy Technology Laboratory. In the case study of class-1 hydrate deposit in the K-site, a constant bottom-hole pressure drop and a constant gas production rate scenario were designed to study the effect of operation conditions on the reservoir behaviors. The constant pressure drop case showed that the recovery factor (RF) was 12.44% with the free gas recovery factor (RF_f) 31.35% and the hydrate recovery factor (RF_h) 7.45%. The gravitational water migration toward the bottom of the gas zone helped to displace the bottom gas. It is suggested that well perforation be placed at the top interval of the gas zone to minimize high water cut production.