Feasibility of gas production from a gas hydrate accumulation at the UBGH2-6 site of the Ulleung basin in the Korean East Sea

Moridis, G.J.,Kim, J.,Reagan, M.T.,Kim, S.J. Elsevier 2013 Journal of petroleum science & engineering Vol.108 No.-

We investigate the feasibility of production from a marine hydrate accumulation that has the properties and conditions of the UBGH2-6 site at the Ulleung basin in the Korean East Sea. The 20m-thick system is in deep water (2160m) but close to the ocean floor (with its top at 140mbsf), and is characterized by alternating mud (near hydrate-free) and sand (hydrate-rich) layers. The layered stratigraphy and the presence of mud layers preclude the use of horizontal wells and necessitate vertical wells. The analysis indicates that production from such a hydrate accumulation is feasible, but the production rates are generally modest. The production rate Q<SUB>p</SUB> peaks at about 1.45STm<SUP>3</SUP>/s=4.4 MMSCFD at about t=1 year, and continuously declines afterward. Sensitivity analysis indicates that cumulative production increases with a declining initial hydrate saturation, an increasing intrinsic permeability of the sand layers and an increasing thermal conductivity of the porous media, while the effect of porosity is non-monotonic: production initially increases with a decreasing porosity, but the trend is later reversed. However, the sensitivity to these parameters is limited, and does not alter the overall predictions of modest production potential. The geomechanical situation appears challenging, as significant subsidence (exceeding 3.5m at a depth of 20m below the sea floor, and 1.5m at the top of the hydrate deposit) is estimated to occur along a large part of the wellbore, and yielding and failure within the 20m-thick system are possible early in the production process. However, there is significant uncertainty in the predictions of the geomechanical system behavior because they are not based on measured system properties but only on estimates/assumptions from analogs.

Prevention of methane hydrate re-formation in transport pipeline using thermodynamic and kinetic hydrate inhibitors

Kim, Jakyung,Kim, Hyunho,Sohn, Young hoon,Chang, Daejun,Seo, Yutaek,Kang, Seong-Pil Elsevier 2017 Journal of petroleum science & engineering Vol.154 No.-

<P><B>Abstract</B></P> <P>Methane gas produced from marine hydrate deposits will flow together with dissociated water in two phases, and the risk of hydrate reformation must be managed. This study used the OLGA multiphase flow simulation software to simulate methane transportation with dissociated water through a vertical 2160m pipeline in order to determine the amount of monoethylene glycol (MEG) as a thermodynamic hydrate inhibitor. When the hydrate saturation ratio in hydrate deposits varies, a large amount of MEG becomes inevitable. Moreover, when undesired water breakthrough occurs, the MEG concentration would decrease to where hydrates may re-form before responding in the offshore platform. A risk management strategy for hydrate reformation is investigated by adopting under-inhibition with MEG and the addition of PVCap as a kinetic hydrate inhibitor (KHI). The experimental results in high pressure autoclave showed that PVCap exhibited a limited performance in delaying the hydrate formation in a high subcooling condition. Considering the vertical flowline of 2160m, the delay time was not sufficient to prevent the hydrate re-formation in the transport pipeline. Complete prevention of hydrate re-formation can be avoided with 35wt% MEG concentration, however decreasing the MEG concentration to 20wt% was also feasible in order to avoid hydrate formation since it was not observed for more than 960min. In the presence of 0.1wt% of PVCap and 10wt% MEG, the hydrate delay time was of about 311.5min. This delay time is 76% longer than the residence time of methane and water mixture in the transport pipeline, thus this synergistic inhibition can significantly reduce the injection rate of MEG while preventing hydrate formation. This is the first work suggesting a risk management strategy for hydrate reformation in hydrate production system, and thus will provide insights to develop advanced hydrate production technologies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Multiphase flow simulation was performed for methane hydrate production. </LI> <LI> Hydrate reformation risk was managed by under-inhibition with MEG. </LI> <LI> Synergistic inhibition with MEG and KHI increased onset time significantly. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

미래 에너지로서 가스 하이드레이트의 개관 및 물리/화학적 특성

차민준,민경원 한국자원공학회 2018 한국자원공학회지 Vol.55 No.6

본 논문에서는 미래 에너지로서 가스 하이드레이트를 이해하기 위해, 가스 하이드레이트의 구조, 물리/화학 적 특성, 생성 기원과 세계 분포, 매장량과 생산기법, 하이드레이트의 지구환경적 영향에 대해 논의하였다. 하이드레 이트의 구조에 대한 명확한 이해는 자연계에 매장된 하이드레이트의 특성 분석, 분포와 매장량 산출에 필수적일 것으 로 판단된다. 안정적인 에너지 회수를 위해 고려해야 할 하이드레이트의 물리/화학적 특성으로는 하이드레이트의 상 평형, 해리 엔탈피, 열전도도, 비열, 열확산도, 유체투과율 등이 있다. 하이드레이트의 물리/화학적 특성을 고려하여 개발된 생산기법으로는 감압법, 열자극법, 억제제 주입법, 맞교환기법이 있으며, 감압법이 현재까지 해상 및 육상 하 이드레이트에 대해 모두 시험생산에 적용된 유일한 기법이다. 또한, 하이드레이트의 해리에 따른 온실가스 배출에 의 한 지구환경적 영향의 가능성에 대해서도 고찰하였다. This paper reviews the structures, physical and chemical properties, origins and global distribution, amount of energy resources, production technologies, and environmental impacts of gas hydrates to understand the gas hydrates as future energy sources. Hydrate structures should be studied to clarify the fundamentals of natural gas hydrates, hydrate distributions, and amount of energy sources in hydrates. Phase equilibria, dissociation enthalpy, thermal conductivity, specific heat, thermal diffusivity, and fluid permeability of gas hydrate systems are important parameters for the the efficient recovery of natural gas from hydrate reservoirs. Depressurization, thermal stimulation, inhibitor injection, and chemical exchange methods can be considered as future technologies to recover the energy sources from natural gas hydrates, but so far depressurization is the only method to have been applied in test productions of both onshore and offshore hydrates. Finally, we discuss the hypotheses of environmental impacts of gas hydrates and their contribution to global warming due to hydrate dissociation.

활성탄과 생물여과 공정에서의 Chloral hydrate 제거 특성

배상대(Sang Dae Bae),손희종(Hee Jong Son),정철우(Chul Woo Jung) 大韓環境工學會 2008 대한환경공학회지 Vol.30 No.2

본 연구에서는 석탄계, 야자계, 목탄계 활성탄과 흡착능이 없는 안트라사이트를 이용하여 클로랄하이드레이트에 대한 흡착 및 생물분해 특성을 평가하였다. 활성탄 공정에서 클로랄하이드레이트의 제거기작은 운전초기에는 흡착이 높은 비중을 차지하나 부착미생물의 활성이 증진되면서 부착미생물에 의한 생분해와 흡착에 의해 제거되었으며, 클로랄하이드레이트는 생분해능이 큰 물질들로 조사되었다. 입상활성탄 재질별 클로랄하이드레이트의 제거 특성은 석탄계와 야자계 활성탄에서 제거율이 높았고, 목탄계는 상대적으로 낮은 제거능을 보였으며, 안트라사이트 biofilter에서 가장 낮은 제거능을 보였다. 활성탄 재질별 부착 미생물의 생체량과 활성도는 석탄계가 가장 높았고, 야자계, 목탄계, 안트라사이트 순으로 나타났으며, 수온 변화에 따른 클로랄하이드레이트의 제거 특성은 수온이 10℃ 이하로 저하될 경우 부착 bacteria의 생체량과 활성도 감소로 제거율이 감소하였다. 안트라사이트를 이용한 생물여과 공정은 수온의 변화에 아주 민감하게 변하는 양상을 나타내었으며, 이는 부착 bacteria에 의한 직접적인 생물분해가 주 제거 메카니즘이기 때문인 것으로 나타났다. 클로랄하이드레이트의 제거시 유입농도가 높은 경우에는 수온의 영향이 매우 중요하며, 흡착능이 소진된 활성탄이나 흡착능이 없는 여재를 사용한 생물여과 공정에서는 수온이 낮은 동절기에는 클로랄하이드레이트의 유출 가능성이 있었다. Coal-, coconut- and wood-based activated carbons and anthracite were tested to evaluate adsorption and biodegradation performances of chloral hydrate. In the early stage of the operation, the adsorption was the main mechanism for the removal of chloral hydrate, however as increasing populations of attached bacteria, the bacteria played a major role in removing chloral hydrate in the activated carbon and anthracite biofilter. It was also investigated that chloral hydrate was readily subjected to biodegrade. The coal- and coconut-based activated carbons were found to be most effective adsorbents in adsorption of chloral hydrate. Highest populations and activity of attached bacteria were shown in the coal-based activated carbon. The populations and activity of attached bacteria decreased in the order: coconut-based activated carbon>wood-based activated carbon>anthracite. The attached bacteria was inhibited in the removal of chloral hydrate at temperatures below 10℃. It was more active at higher water temperatures(20℃<) but less active at lower water temperature(10℃>). The removal efficiencies of chloral hydrate obtained by using four different adsorbents were directly related to the water temperatures. Water temperature was the most important factor for removal of chloral hydrate in the anthracite biofilter because the removal of chloral hydrate depended mainly on biodegradation. Therefore, the main removal mechanism of chloral hydrate by applying activated carbon was both adsorption and biodegradation by the attached bacteria. The observation suggests that the application of coal- based activated carbon to the water treatment should be the best for the removal of chloral hydrate.

Estimation of model parameters and properties for numerical simulation on geomechanical stability of gas hydrate production in the Ulleung Basin, East Sea, Korea

Kim, Ah-Ram,Kim, Hak-Sung,Cho, Gye-Chun,Lee, Joo Yong Elsevier 2017 QUATERNARY INTERNATIONAL Vol.459 No.-

<P><B>Abstract</B></P> <P>The process of hydrate dissociation and production induced by depressurization incorporates intricate hydraulic, thermal, and mechanical phenomena. Thus, coupled thermal-hydraulic-mechanical (T-H-M) simulation is critically necessary to evaluate the geomechanical stability of hydrate production in hydrate-bearing sediments (HBS). However, methods of estimating the input model parameters and properties of the target reservoir, in particular in unconsolidated marine sediments, have received limited attention compared to studies on production simulators. The T-H-M properties of the marine sediments change considerably with depth, geological strata, and soil type of each layer. Therefore, it is important that representative layers and their corresponding T-H-M properties should be properly estimated to analyze the stability and productivity of methane gas recovery in the field. This study provides a comprehensive estimation for the model parameters and properties of unconsolidated marine sediments, based on vast data from field seismic surveys and laboratory experimental results with core samples, investigates empirical correlations between model parameters and methane hydrate saturation, and finally summarizes the estimated model parameters and properties, which can possibly be applied to on-going numerical research into stability assessment of the pilot gas hydrate (GH) production test, which is soon to be performed in the Ulleung basin.</P>

가스하이드레이트 개발 국제 동향과 특허 분석

김대형,이재욱 한국자원공학회 2010 한국자원공학회지 Vol.47 No.4

Gas hydrates are solid crystalline compounds in which gas reside inside cages formed by hydrogen-bonded water molecules in a crystalline lattice. As the world wide estimated resources of gas hydrate is so huge (between 1016 to 1019 SCF), after 21 century, a lot of research work for the commercial use of gas hydrate is conducted. In this study, recent important gas hydrate R&D trends & programs were reviewed, and carried out several analyses on patent documents for techniques of gas hydrate exploration and production. The patents including abstracts, claims and drawings from 1975 up to 2008 were surveyed and 141 patents were collected finally. The patents were investigated as to countries, assignees, and techniques. As a result, we suggested implications for effective policy of patent application and management on gas hydrate. 천연가스가 저온, 고압 하에서 물 분자와 결합되어 형성된 고체 물질로 주성분이 메탄으로 구성되어 있는 가스하이드레이트는 국제적으로 광범위하게 분포된 부존과 막대한 매장량으로 인해 기존의 석유, 가스를 대체할 새로운 에너지원으로 국제적 관심을 받고 있다. 특히 2000년 대 중반 이후 석유 등 화석연료 가격이 폭등하면서 국제적으로 가스하이드레이트의 상업적 개발, 생산 및 이용을 위한 다양한 연구들이 이루어진 바 있다. 본고에서는 가스하이드레이트의 조사·탐사, 개발, 생산과 관련하여 국제적으로 이루어진 대표적인 연구 및 개발 프로젝트의 최근 동향을 살펴보았다. 또한 1975-2008년까지의 가스하이드레이트 조사·탐사, 개발·생산 및 안전성 관련 국내외 특허 141건을 분석하여, 국제적 기술 흐름의 추세와 함께 특허보유 국가 및 출원인을 분석하였으며, 향후 효과적인 특허 출원 및 관리를 위한 시준점을 제시하였다.

가스하이드레이트 시험생산 기술개발 동향

박승수(Park, Seoung-Soo),주우성(Ju, Woo-Sung),안승희(An, Seung-Hee),이정환(Lee, Jeong-Hwan) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06

For the Gas hydrate Research and Development in Korea, the prospect area I & II was surveyed and drilled during the first phase. At the result, we succeeded to discovering gas hydrate real sample at BSR reflection and vent structure. This expedition processing contributes to developing the offshore seismic survey technologies and data processing of Korea. But Korean gas hydrate test production research, in spite of activating test production at other countries, is such a limitation about technician, GH production technologies and E&P processing. First of all, there is no exist in Korea to application site for the their production research results. In this paper, we have studied the gas hydrate reservoir selection technics of the DOE & BPXA for the ANS test production. And this result will helpful to preparation of gas hydrate test production in Korea.

가스하이드레이트 생산기술 개발현황 및 미래전망

이정환 한국자원공학회 2009 한국자원공학회지 Vol.46 No.3

Research and development projects have been world widely carried out to develop the technology to produce gas from gas hydrate that have a high potential, as a future new energy. However commercial production is not achieved yet due to the technical problems and the high risks. In hydrate-bearing layer, it is required the technology to enhance gas recovery by dissociation, process to gasify gas hydrate that is solid state. The problems related to structure change or stability of sedimentary layer should be solved in this process. This study presents the possibilities of recovery and the value of future for gas hydrate as an energy resource by reviewing the commercial condition, methodology, and current state of development techniques. Especially, it has been presented the comparison of technological difference and the direction to progress the technology in Korea by investigating the international pilot production test. 미래의 신 에너지원으로서 높은 잠재력을 가지고 있는 가스하이드레이트의 개발 및 생산에 필요한 기술은 전 세계적으로 연구개발 중에 있으나 기술적 난제와 개발 위험성으로 인해 아직 상업적 목적의 산업화 단계까지는 도달되지 않은 상태이다. 가스하이드레이트층의 경우 고체상태인 하이드레이트를 기체화시키는 과정, 즉 해리를 촉진시켜 가스의 회수율을 높이는 기술이 요구되며 이 과정에서 퇴적층의 구조변화 혹은 안정성 문제가 해결되어야 한다. 본 연구에서는 가스하이드레이트의 상업적 생산조건 및 방법론, 생산 기술개발 현황을 고찰함으로써 에너지원으로서의 가스하이드레이트 생산 가능성 및 미래가치를 조망하였다. 특히 국제 공동 시험생산 프로젝트 추진현황 분석을 통해 국내 기술수준을 비교하고 향후 국내 가스하이드레이트 기술개발 방향을 제시하였다.

동해 울릉분지 가스하이드레이트 퇴적층의 생산 영향 인자 변화에 따른 해리유동 분석

신효진,김지수,임종세,김세준 한국자원공학회 2015 한국자원공학회지 Vol.52 No.5

It is assumed that huge amounts of gas hydrate(GH) are buried in the Ulleung basin, East Sea of Korea. In order to develop the GH, production test should be carried out on the basis of the analysis reflected field conditions. In this study, numerical simulation model was composed based on the geological system at field production test site. Also, GH dissociation and flow behavior for productivity influence factors was analyzed to prepare history matching after production test. As a result, low-temperature distribution was extended in case of the small value of bottom hole pressure, and gas production was increased because decompression phenomenon occurs significantly in nearby production well. The smaller permeability anisotropy value, improved horizontal flow caused the increased gas production. Consequently, it is possible to use the preliminary analysis of GH field production test through the results derived by assuming a variety of production scenarios and sedimentary property. 동해 울릉분지에는 막대한 부존량으로 높은 잠재력을 지닌 가스하이드레이트가 부존되어 있으며, 이를개발하기 위해서는 현장조건을 반영한 분석을 토대로 시험생산이 이루어져야 한다. 이 연구에서는 현장 시험생산 후보지의 지질학적 구조를 바탕으로 전산 수치 모델을 구성하였으며, 향후 시험생산 수행 후 히스토리매칭작업을 대비하기 위해 생산 영향 인자에 대한 해리유동 전산 수치 분석을 수행하였다. 그 결과 공저압이 낮을수록 생산정 부근에서 감압현상이 크게 발생하여 저온 분포가 확대되고 가스 생산량이 증가하였으며, 유체투과도이방성의 경우 값이 작을수록 수평방향 유동이 향상되어 증가한 가스 생산량을 보였다. 따라서 다양한 생산시나리오와 퇴적층 물성을 가정하여 도출한 결과를 통해 가스하이드레이트 현장 시험생산 계획 수립 시 요구되는 예비 분석 자료로 이용 가능할 것이다.

Physicochemical properties and autogenous healing performance of ternary blended binders composed of OPC-BFS-CSA clinker

H.N. Yoon,Joonho Seo,Naru Kim,H.M. Son,H.K. Lee Techno-Press 2023 Advances in concrete construction Vol.15 No.1

Autogenous healing of concrete can be helpful in structural maintenance by healing cracks using a healing material created by the precipitation of calcite and by the hydration of unhydrated binder around the cracks. Against this backdrop, this study investigated the physicochemical properties and autogenous healing performance of ternary blended binder composed of ordinary Portland cement (OPC), blast furnace slag (BFS), and calcium sulfoaluminate (CSA) clinker. Ternary blended binders with various contents of OPC-BFS-CSA clinker were prepared, and their physicochemical properties and autogenous healing performances were examined using various analytical techniques and visually observed using a microscope. The obtained results indicated that increase in the BFS content accompanied the increased the amount of unreacted BFS even after 28 days of curing and had a positive effect on the autogenous healing performance due to its latent hydration. However, replacing the CSA clinker did not increase the autogenous healing performance owing to an insufficient sulfate source for the formation of ettringite. The main precipitates around the cracks were calcite, C-S-H. Other hydration products such as portlandite, monosulfate, and ettringite, which were not found in the Raman and scanning electron microscope analyses.