The use of huff and puff method in a single horizontal well in gas production from marine gas hydrate deposits in the Shenhu Area of South China Sea

Abstract The Shenhu Area is located in the Pearl River Mouth Basin, the northern continental slope of the South China Sea. It is expected that the Shenhu Area will become a strategic area of gas hydrate exploitation in China. Based on currently available data from site measurements, including water depth, thickness of the Hydrate-Bearing Layer (HBL), sediment porosity, salinity and pressures and temperatures at key locations, it is possible to develop preliminarily estimates of the gas production potential by numerical modeling. We used measurements of ambient temperature in the sediments to determine the local geothermal gradient. Estimates of the hydrate saturation and the intrinsic permeabilities of the system formations were obtained from direct measurements. The hydrate accumulations in the Shenhu Area are similar to Class 3 deposits (involving only an HBL), and the overburden and underburden layers are assumed to be permeable. These unconfined deposits may represent a large challenge for gas production. In this modeling study, we estimated gas production from hydrates at the SH7 drilling site of the Shenhu Area by means of the stream huff and puff method using a single horizontal well in the middle of the HBL. The simulation results indicate that the hydrate dissociated zone expands around the well, and the hydrate formation occurs during the injection stage of the huff and puff process. The higher temperature of the injected brine appears to have a limited effect on gas production using the huff and puff method. Reasonable injection and production rates should be adopted to avoid the over pressurization and depressurization during each huff and puff cycle. Production is invariably lower than that attainable in a confined system, and thermal stimulation is shown to have an effect over a limited range around the well. The sensitivity analysis demonstrates the dependence of gas production on the level of the increment of the injection and production rates of the huff and puff process, the temperature of the injected brine and the existence of brine injection during the injection stage.

[1]  Matthew T. Reagan,et al.  Sensitivity Analysis of Gas Production from Class 2 and Class 3 Hydrate Deposits , 2008 .

[2]  T. Komai,et al.  Experimental Study On Steam Injection Method Using Methane Hydrate Core Samples , 2007 .

[3]  George J. Moridis,et al.  Toward Production From Gas Hydrates: Current Status, Assessment of Resources, and Simulation-Based Evaluation of Technology and Potential , 2008 .

[4]  George J. Moridis,et al.  Evaluation of Gas Production Potential from Marine Gas Hydrate Deposits in Shenhu Area of South China Sea , 2010 .

[5]  Goodarz Ahmadi,et al.  Production of natural gas from methane hydrate by a constant downhole pressure well , 2007 .

[6]  George J. Moridis,et al.  Gas Production From Oceanic Class 2 Hydrate Accumulations , 2007 .

[7]  B. B. Maini,et al.  Laboratory evaluation of the CO2 huff-n-puff process for heavy oil reservoirs , 1983 .

[8]  George J. Moridis,et al.  Depressurization-induced gas production from Class 1 hydratedeposits , 2005 .

[9]  M. Kowalsky,et al.  TOUGH+Hydrate v1.0 User's Manual: A Code for the Simulation of System Behavior in Hydrate-Bearing Geologic Media , 2008 .

[10]  M. Reagan,et al.  Strategies for gas production from oceanic Class 3 hydrate accumulations , 2007 .

[11]  Liang-Guang Tang,et al.  Control Mechanisms for Methane Hydrate Production by Thermal Stimulation , 2010 .

[12]  B. Tohidi,et al.  Experimental determination and prediction of methane hydrate stability in alcohols and electrolyte solutions , 2009 .

[13]  Kefeng Yan,et al.  Experimental Investigation into the Production Behavior of Methane Hydrate in Porous Sediment with Hot Brine Stimulation , 2008 .

[14]  Keni Zhang,et al.  EVALUATION OF THE GAS PRODUCTION POTENTIAL OF CHALLENGING HYDRATE DEPOSITS , 2009 .

[15]  George J. Moridis,et al.  Evaluation of the Gas Production Potential of Marine Hydrate Deposits in the Ulleung Basin of the Korean East Sea , 2007 .

[16]  H. David.  Geoscientists in the Peace Corps; a strategic revisit , 2004 .

[17]  Xiao-Sen Li,et al.  Experimental Investigation of Production Behavior of Methane Hydrate under Ethylene Glycol Injection in Unconsolidated Sediment , 2007 .

[18]  Van Genuchten,et al.  A closed-form equation for predicting the hydraulic conductivity of unsaturated soils , 1980 .

[19]  R. Leaute,et al.  Liquid Addition to Steam for Enhancing Recovery (LASER) of Bitumen With CSS: Results From the First Pilot Cycle , 2007 .

[20]  Fan Shuanshi.  Thermodynamic evaluation of hot brine stimulation for natural gas hydrate dissociation , 2006 .

[21]  George J. Moridis,et al.  Comparison of kinetic and equilibrium reaction models in simulating gas hydrate behavior in porous media , 2006 .

[22]  E. Vittoratos.  Flow Regimes During Cyclic Steam Stimulation At Cold Lake , 1991 .

[23]  M. Max,et al.  Tectono-sedimentary controls on the likelihood of gas hydrate occurrence near Taiwan , 2000 .

[24]  M. Clarke,et al.  Determination of the intrinsic rate of ethane gas hydrate decomposition , 2000 .

[25]  Carolyn A. Koh,et al.  Clathrate hydrates of natural gases , 1990 .

[26]  M. H. Yousif,et al.  Experimental and Theoretical Investigation of Methane-Gas-Hydrate Dissociation in Porous Media , 1991 .

[27]  Wang Hong-bin,et al.  PRELIMINARY DISCUSSION ON NATURAL GAS HYDRATE (NGH) RESERVOIR SYSTEM OF SHENHU AREA,NORTH SLOPE OF SOUTH CHINA SEA , 2007 .

[28]  S. Sayegh,et al.  Laboratory Evaluation Of The CO Huff-N-Puff Process For Heavy Oil Reservoirs , 1984 .

[29]  Jeffery B. Klauda,et al.  Global Distribution of Methane Hydrate in Ocean Sediment , 2005 .

[30]  George J. Moridis,et al.  A Domain Decomposition Approach for Large-Scale Simulations of Flow Processes in Hydrate-Bearing Geologic Media , 2008 .