Alaska North Slope Gas Hydrate Energy Resources

Transcription

1 USGS pen File Reprt Alaska Nrth Slpe Gas Hydrate Energy Resurces By Timthy S. Cllett In late Nvember 2004, the Alaska State Legislature requested the U.S. Gelgical Survey (USGS) t prvide a technical briefing n the energy resurce ptential f gas hydrates in nrthern Alaska at the Federal Energy Regulatry Cmmissin (FERC) Technical Cnference fr Regulatins Gverning the Cnduct f pen Seasns fr Alaska Natural Gas Transprtatin Prjects, Dcket N. RM , scheduled fr December 3, 2004, in Anchrage, Alaska. In respnse t this request, Dr. Timthy S. Cllett f the USGS participated in the FERC-hsted cnference, and presented a brief verview f the energy resurce ptential f gas hydrates in nrthern Alaska. This reprt summarizes Dr. Cllett s presentatin at the cnference, in which he discussed the issue under the FERC Ntice f Prpsed Rule Making that addresses the amunt f Alaska Nrth Slpe gas ptentially available fr transprt thrugh an Alaska gas pipeline. Gas hydrates are naturally ccurring ice-like substances cmpsed f water and gas. Gas hydrates are widespread in permafrst regins and beneath the sea in sediment f uter cntinental margins. The amunt f natural gas sequestered in gas hydrates is prbably enrmus, but estimates f the amunts are highly speculative. In 1995, the USGS cnducted the first systematic assessment f the in-place natural gas hydrate resurces f the United States. That study suggested that the amunt f gas in the Natin s hydrate accumulatins greatly 1

2 exceeds the vlume f knwn cnventinal dmestic gas resurces. The 1995 USGS assessment als estimated that the permafrst-assciated gas hydrates n the Alaska Nrth Slpe may cntain as much as 590 trillin cubic feet f in-place gas (fig. 1). Tw large gas hydrate accumulatins have been identified near the Prudhe Bay il Field (fig. 2). The vlume f gas estimated within the knwn gas hydrates f the Prudhe Bay- Kuparuk River infrastructure area alne may exceed 100 trillin cubic feet f in-place gas. Hwever, it is imprtant t nte that nne f the cmpleted gas hydrate energy assessments have predicted hw much gas culd actually be prduced frm the knwn gas hydrate accumulatins in nrthern Alaska. Under the Methane Hydrate Research and Develpment Act f 2000, the U.S. Department f Energy (DE) funds labratry and field research n bth Arctic and marine gas hydrates. Amng the current Arctic studies, BP Explratin (Alaska), Inc. and the DE have undertaken a prject t characterize, quantify, and determine the cmmercial viability f gas hydrates and assciated free gas resurces in the Prudhe Bay, Kuparuk River, and Milne Pint field areas n the Alaska Nrth Slpe. Ultimately, this prject culd determine if gas hydrates can becme a part f the Alaska Nrth Slpe gas-resurce prtfli. Als in nrthern Alaska, the Bureau f Land Management, the Alaska Divisin f Gelgical and Gephysical Surveys, and the USGS are assessing the resurce ptential f gas hydrates ver the entire area, including the Natinal Petrleum Reserve Alaska, Arctic Natinal Wildlife Refuge, and the State and Native lands nrth f the Brks Range. The gal f this jint prject is t assess the ecnmically recverable resurce ptential f gas hydrates and assciated free gas accumulatins in nrthern Alaska. 2

3 The prductin ptential f the Alaska Nrth Slpe gas hydrate accumulatins has nt been adequately tested. Althugh unverified by field testing, prductin mdels f gas hydratebearing reservirs within prspects interpreted frm seismic and well data in the Milne Pint area (fig. 2) suggest that sustained prductin rates f several millin cubic feet f gas per day can be achieved. In December 2003, the Canadian Mallik 2002 Gas Hydrate Prductin Research Well Prgram partners (including the USGS and the DE) publicly released the results f the first mdern, fully integrated field study and cnstrained prductin test f a natural gas hydrate accumulatin. The Mallik 2002 gas hydrate prductin testing and mdeling effrt has, fr the first time, enabled ratinal assessment f the prductin respnse f a gas hydrate accumulatin. Prject-supprted gas hydrate prductin simulatins have shwn that under certain gelgic cnditins gas can be prduced frm gas hydrates at rates exceeding several millin cubic feet f gas per day. A grwing bdy f evidence suggests that a huge vlume f natural gas is stred as gas hydrates in nrthern Alaska and that prductin f natural gas frm gas hydrates may be technically feasible. Hwever, numerus technical challenges must be reslved befre this ptential resurce can be cnsidered an ecnmically prducible reserve. Figures Figure 1. This map depicts the area in nrthern Alaska in which subsurface temperature and pre-pressure cnditins are cnducive t the ccurrence f gas hydrates. Als shwn is the lcatin f the Eileen and Tarn gas hydrate accumulatins in the Prudhe Bay area. NPRA = Natinal Petrleum Reserve in Alaska; ANWR = Arctic Natinal Wildlife Refuge. 3

4 Figure 2. This map depicts the distributin f the Eileen and Tarn gas hydrate accumulatins in the area f the Prudhe Bay, Kuparuk River, and Milne Pint il fields n the Nrth Slpe f Alaska. 4

5 Figure 1. This map depicts the area in nrthern Alaska in which subsurface temperature and pre-pressure cnditins are cnducive t the ccurrence f gas hydrates. Als shwn is the lcatin f the Eileen and Tarn gas hydrate accumulatins in the Prudhe Bay area. NPRA = Natinal Petrleum Reserve in Alaska; ANWR = Arctic Natinal Wildlife Refuge. km Pint Barrw ARCTIC CEAN mi 71 Prudhe Bay NPRA Eileen and Tarn Gas Hydate Accumulatins Figure 2 ANWR Zne f Ptential Gas Hydrate Stability 69 U. S. Gelgical Survey pen File Reprt

6 Figure 2. This map depicts the distributin f the Eileen and Tarn gas hydrate accumulatins in the area f the Prudhe Bay, Kuparuk River, and Milne Pint il fields n the Nrth Slpe f Alaska. 0 5 km 0 3 mi Tarn Accumulatin MILNE PINT IL FIELD FREE GAS Till #1 Arc Clville River #1 KUPARUK RIVER IL FIELD PRUDHE BAY IL FIELD Eileen Accumulatin Cirque #2 Cirque #1 West Sak #20 Ht Ice #1 GAS HYDRATE GAS HYDRATE U. S. Gelgical Survey pen File Reprt