본 연구에서는 가상의『흑곰-HY』가스전을 대상으로 상용저류전산시뮬레이터인『ECLIPSE 300』을 사용하여 가스저장전으로 전환에 대비한 기술적 타당성을 평가하고자 하였다. 이 저류층의 매장량은 143 BCF로서 소규모 가스전이며, 공극률과 투과도는 각각 19.5%와 50 md로 가스의 순환이 원활이 이루어질 수 있는 비교적 양호한 저류층이다. 이 저류층에 대하여 가스저장전으로의 전환시 핵심적 검토항목인 쿠션가스 양, 저장전으로의 전환시점, 운영사이클 변경, 가스정의 수 및 수평정 적용 가능성 등에 대한 분석을 수행하였다. 분석결과,『흑곰-HY』가스저장전에서 안정적인 가스저장을 위해서는 쿠션가스가 최소한 50% 이상이 되어야 함을 알 수 있었다. 또한 가스를 더 오랜기간동안 생산하기 위해 잔류가스를 적정 쿠션가스 양보다 적게 남겨두어도 추가로 쿠션가스만 주입하면 기술적으로는 아무 문제가 없는 것으로 나타났다. 한편, 가스를 5개월 대신 동절기 3개월간만 재생산하는 운영사이클의 경우에는 쿠션가스를 60% 이상으로 높여주거나 가스정의 수를 늘려야만 재생산이 가능한 것으로 나타났다. 가스정의 수에 대한 분석결과에서는 6개와 8개인 경우에는 저류층내 잔류가스가 증가하여 정상적인 재생산이 불가능하므로『흑곰-HY』가스전에서는 최소 10개의 수직가스정이 운영되어야 함을 알 수 있었다. 이에 반해 2개의 기존 수직정에 3개의 수평정을 추가로 시추하게 되면 비교적 안정적인 주입과 재생산이 가능한 것으로 산출되었다.

In this study we have attempted to evaluate the technical feasibility of 『BB-HY』, which is depleted gas reservoir as a gas storage field, using the commercial compositional simulator『ECLIPSE 300』. The『BB-HY』 reservoir has an initial gas in place of 143 BCF which is relatively small, and its porosity and permeability are 19.5% and 50 md, respectively. For 『BB-HY』 gas reservoir, we have performed a feasibility analysis by investigating the cushion gas (or working gas), converting time to gas storage field, operation cycle, number of wells and the possible application of horizontal borehole as well. From the simulation results, it was found that the amount of cushion gas in 『BB-HY』reservoir is required at least 50% of IGIP in order to operate stably as gas storage field. When one produces gas for longer time and hence the remaining gas in reservoir is less than optimal cushion gas, no technical problem was occurred as long as additional cushion gas is injected up to the optimal cushion gas. In the case of changing the operation cycle into producing gas for three months during winter season from producing five months, the result shows that either the cushion gas should be greater than 60% or the more number of wells should be drilled. Meanwhile, from the results of sensitivity analysis for the number of wells, in cases of operating six or eight vertical wells, the stable reproduction of the injected gas can not be possible in 『BB-HY』gas reservoir since the remaining gas in reservoir is increased. Therefore, in 『BB-HY』 reservoir, at least ten vertical wells should be drilled for the stable operation of gas. This time, when three horizontal wells are additionally drilled including the existing two vertical wells, it was found that the operation of injection and reproduction of gas is relatively stable in『BB-HY』gas reservoir.

Gas Storage Depleted Gas Reservoir Cushion Gas Working Gas Simulation Vertical Well Horizontal Well

Katz DL, Tek MR, JPT, 33(6), 943 (1981)
Mayfield JF, JPT, 33(9), 1731 (1981)
Sung WM, Ryou SS, Ra SH, Kwon SI, Korean J. Chem. Eng., 18(1), 67 (2001)
Knepper GA, Cuthbert JF, paper SPE 8412 presented at the 54th Annual Fall Technical Conference and Exhibition of the Society of Petroleum Engineers, Las vegas, Nevada, September (1979)
Chung CB, Korean J. Chem. Eng., 8(4), 240 (1991)
Gredell ME, Benson MA, Oil Gas J., 93(50), 60 (1995)
Baird JL, paper SPE 7171 presented at the Rocky Mountain Regional Meeting of the Society of Petroleum Engineers, Cody, U.S.A., May (1978)
Bennion DB, Thomas FB, Ma T, Imer D, paper SPE 59738 presented at the SPE/CERI Gas Technology Symposium, Calgary, Alberta, Canada, April (2000)
Kim MS, Ryon SS, Geosystem Eng., 38(5), 379 (2001)
Misra SE, Foh SE, Shikari RM, paper SPE 17741 Presented at the Gas Technology Symposium, Dallas, U.S.A., June (1988)