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Couves C.,UK National Oceanography Center | Roberts S.,UK National Oceanography Center | Racey A.,Andy Racey Geoscience | Troth I.,BG Group | Best A.,UK National Oceanography Center
Journal of Petroleum Geology

Basaltic lava flows and ignimbrite units around Puerto de Santiago, SW Tenerife, were investigated as potential analogues for hydrocarbon-bearing volcanic reservoir rocks. Conventional helium porosity and air permeability measurements together with the results of a micro-focus X-ray computed tomography study were integrated with field observations on flow morphology and the continuity of defined internal lava flow zones. Individual lava flows typically comprise distinct tops, cores and bases, with lava piles showing repeated cycles of these three internal zones. Reservoir quality is best in the flow tops (mean φ{symbol} = 23.14%, k = 5.622mD) where vesicular porosity dominates. Flow cores are relatively tight with primary porosity mainly controlled by cooling joints, fractures and intercrystalline microporosity (mean φ{symbol} = 2.40%, k = 0.001mD). Flow bases show variable reservoir potential due to the presence of breccia and/or vesiculation (mean φ{symbol} = 11.77%, k = 0.001mD). By contrast, ignimbrites show the highest porosities but have low permeabilities (mean φ{symbol} = 35.64%, k = 0.0056mD). In all cases, the primary porosity and permeability may have been modified to create additional secondary porosity and permeability as a result of fracturing and mineral dissolution during burial or weathering, although porosity may also be occluded through the precipitation of secondary minerals or the alteration of primary minerals. The new porosity data presented demonstrates that pyroclastics and basaltic lava flow tops have the best reservoir properties, with the flow tops having sufficient porosity and permeability to transmit fluids and gas. In contrast, flow cores are relatively tight (impermeable), and would act as seals to potential hydrocarbon accumulations when fractures and cooling joints are absent. The reservoir potential can be high where vesicles and fractures are present (i.e. in lava flow tops), although there is uncertainty whether flow tops could be connected to each other vertically to form a potentially exploitable hydrocarbon reservoir. Although in some areas such volcanic rocks can be primary targets for hydrocarbon exploration (e.g. onshore China), in many others they are considered to be a secondary target, adding incremental resources to hydrocarbons produced from more conventional sandstone and carbonate reservoirs. © 2016 Scientific Press Ltd. Source

Ridd M.F.,43 Prospect Quay | Racey A.,Andy Racey Geoscience
Geological Society Memoir

Before the birth of the modern, mechanized, petroleum industry, Myanmar (formerly Burma) was an exporter of oil products from its hand-dug wells in the centre of the country. It is now an important exporter again, but of gas from its offshore fields, and the international petroleum companies are keen to obtain acreage both onshore and offshore; in the lead-up to the 2013 offshore round no fewer than 60 companies pre-qualified with the Ministry of Energy of the Myanmar government. © 2015 The Authors. Published by The Geological Society of London. All rights reserved. Source

Racey A.,Andy Racey Geoscience | Ridd M.F.,43 Prospect Quay
Geological Society Memoir

Rakhine (formerly Arakan) is the name of the Myanmar state that extends almost the whole length of the Bay of Bengal coast from the Bangladesh border south to about latitude 17°30', and inland to the watershed of the Indo-Burman Ranges. The Myanmar government adopted the name for the northernmost of its offshore petroleum regions, and their Rakhine Region comprises the offshore blocks A1-A7 and deep-water blocks AD1-AD16 (Fig. 9.1). Much of that offshore region is occupied by the Rakhine Basin which also extends onshore beneath the Rakhine Coastal Lowlands, and this chapter discusses the petroleum geology of both the Rakhine Region (i.e. offshore) in which the Shwe gas field is located and the Rakhine Coastal Lowlands (onshore) in which a number of small oil discoveries have been made. The Rakhine Coastal Lowlands represents the southwards extension of the hydrocarbon-bearing regions of Assam and eastern Bangladesh. The offshore Rakhine Region covers an area of 170 000 km2 and has a Tertiary clastic sedimentary fill of several kilometres. The Rakhine Basin is subdivided into: (1) a structurally complex onshore and offshore shelf area; and (2) a poorly structured deepwater area. The two are separated by a dextral trench-parallel shear fault system which represents the boundary between the India Plate in the west and the Burma Platelet in the east. © 2015 The Authors. Source

Racey A.,Andy Racey Geoscience | Ridd M.F.,43 Prospect Quay
Geological Society Memoir

While the focus of this volume is Myanmar, some of the basins that are the subject of earlier chapters extend into adjoining countries or their offshore exclusive economic zones (EEZs). In this chapter we look briefly at the progress of exploration in adjoining areas of India (the Andaman Islands), Bangladesh and Thailand. We see that success has so far eluded exploration in Thailand's EEZ and that of the Andaman Islands, despite seismic and drilling activities over several decades. On the other hand, north from Myanmar's Rakhine Basin (offshore and onshore) in Bangladesh, substantial gas reserves have been discovered and developed. © 2015 The Authors. Source

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