A re-evaluation of a fractured carbonate reservoir from the Perth Basin, Western Australia (original) (raw)

Classification of Fractured Carbonate Reservoirs_A.J.docx

Some researchers classified the fractured carbonate reservoirs as one of four types (Hubert and Willis (1955) and MacNaughton and Garb (1975); modified by Nelson, 1985; Allen and Sun, 2003, 2004). Their argument based on intergranular porosity and permeability and the role of fractures which has play role in providing space and fluid flow. Depending of rock type , local tectonic regime and thickness of sediment the fracture pattern can be change.

A Snapshot of Carbonate Reservoir Evaluation

Oilfield Review

Carbonate reservoir evaluation has been a high priority for researchers and oil and gas producers for decades, but the challenges presented by these highly heterogeneous rocks seem to be never-ending. From initial exploration through mature stages of production, geoscientists, petrophysicists and engineers work together to extract as much information as possible from their data to produce maximum reserves from the ground. Carbonate reservoirs present a picture of extremes. Reservoirs can be colossal though their pores can be microscopic (next page, top). Matrix permeability can be immeasurably low, while fluids flow like rivers through fractures. Evaluation techniques that succeed in sandstone reservoirs sometimes fail in carbonate reservoirs. These variations complicate both reservoir evalu-ation and hydrocarbon recovery. However, researchers are working to overcome these prob-lems because of the economic significance of oil production from carbonate reservoirs, especially giant an...

Identification of Fractures and Karstified Zones in Carbonate Reservoirs using Geophysical Logs

Abstracts Volume (CD-ROM), 6 pp., 2009

Carbonate (limestone and dolomite) reservoirs are important exploration targets from the perspective of oil/gas and, also, groundwater reserves. In this respect, the most important aquifer system in Romania is located in the Upper Jurassic - Lower Cretaceous carbonate formations from South Dobrogea region. The porosity of carbonate rocks can be grouped into three types: connected porosity between the carbonate grains, vugs (unconnected pores resulting from the dissolution of calcite by water) and fracture porosity caused by tectonic stresses. These forms of porosity create a very complex path for fluids and, as well, have an impact on the response of geophysical logging tools. Most carbonate reservoirs are naturally fractured, the fractures existing at all scales, from microscopic fissures to kilometer sized structures called fracture swarms or corridors, creating complex networks in the reservoir. Large fracture corridors can be significant flow routes for the fluids in such reservoirs, so knowing their position is critical for planning new wells and for simulating and forecasting reservoir production.

From fractures to flow: A field-based quantitative analysis of an outcropping carbonate reservoir

Tectonophysics, 2010

Fractures can play an important role in the fluid storage-migration properties of fault damage zones. In this present contribution, we document the role exerted by fractures on fluid flow in carbonate damage zones of hydrocarbon-bearing, km-long, oblique-slip normal faults with 10's of m-throw. The carbonate fault damage zones were analysed by mean of scan line surveys conducted in both tar-free and tar-rich outcrops. In this way, the relationships among the individual fracture characteristics (length, spacing, aperture, orientation, connectivity and distance from slip surfaces pertaining to small faults of the fault damage zones) and hydrocarbons have been established. Data obtained by scan line surveys were also used to compute the amount of fracture porosity, the degree of fracture connectivity and, based upon simple assumptions, the orientation of the local σ hmax at times of faulting. Additionally, scan line surveys were also carried out along outcrops exposing unfaulted carbonate host rocks. The results of our computation are consistent with a carbonate host rock made up of a quite isotropic fracture array comprised of isolated and coupled fractures, in which individual fracture sets have negative exponential spacing distributions. In terms of fluid flow, the fracture array of the carbonate host rock enhances the fluid storage. Conversely, the fracture array of the fault damage zones is characterized by a pronounced anisotropy due to interconnected fractures, which enhance the fluid migration. Fractures in the fault damage zones include those inherited from background deformation and others related to the faulting processes. The latter fracture sets are characterized by power law spacing distributions. In conclusion, counter-intuitively, both fracture length and fracture spacing do not have any correlation with hydrocarbons in the fault damage zones. On the contrary, fracture anisotropy, fracture spread and fracture orientation are positively correlated with hydrocarbons.

Reservoir potential of carbonate rocks in the Kutai Basin region, East Kalimantan, Indonesia

Journal of Asian Earth Sciences, 1999

Fifteen percent of the exploration wells drilled in the Kutai Basin region were targeted for stratigraphic play-types. Carbonate reservoirs comprise almost 70% of the objectives in these stratigraphic plays. There was need for a better understanding of the carbonate reservoir potential in the region. Accordingly, this study was carried out. The distribution, depositional environment as well as factors controlling the quality of carbonate reservoirs are reviewed and analyzed. Carbonate reservoirs in the study area can be found sparsely throughout the Kutai Basin. Carbonates range in age from Oligocene (Bebulu limestone) to Late Miocene (Dian limestone). The main constituents of these carbonate build-ups are platy-corals, encrusting red algae and larger benthonic foraminifera. Most of the carbonates were deposited in a shallow marine environment (inner to middle shelf) during rises in relative sea level. Highstand system tracts are characterized by well-developed carbonate facies-belts. The carbonate build-ups generally occur as isolated bedded mounds, from a few feet up to 1000 ft in thickness. The preservation of primary porosity is generally poor due to diagenetic processes during burial history, particularly the in®lling of pores by non-ferroan calcite cement. The development of secondary porosity is limited, due to the retardation of subsurface¯uid¯ow by nonpermeable layers, and the absence of solution eects due to sub-aerial exposure and karsti®cation. Preserved porosities are mainly present as vugs, best developed in coarse-grained shelf-margin facies, which may not have subsequently been completely ®lled by calcite cement. Early hydrocarbon migration may retard the diagenetic processes and preserve the primary carbonate porosity.

Classification of Fractured Carbonate Reservoirs

Advances in Characterization and Modeling of Complex Carbonate Reservoirs

2015

Welcome to the inaugural CSPG-SEPM Mountjoy carbonate meeting, named in honour of Eric Mountjoy. Mountjoy was a legend in the innovative study of limestones and dolomites and in particular understood the importance of discussion and field work for the generation and testing of new ideas. In this spirit the technical committee, along with the session chairs, has worked over the past two years to compile what we hope will be an invigorating program of both talks and field trips that captures the latest developments in carbonate reservoir characterization and modeling. Many of the talks cut across session themes, highlighting the inter-disciplinary nature of our science and the methods used in petroleum exploration and development. We have embedded a number of field trips in the middle of the meeting, as well as a post-meeting field trip. These offer a great opportunity to see some world-class localities in the Canadian Rockies, to network and discuss with other delegates, and to stretch your legs! To conclude the meeting, we are displaying a variety of cores from different carbonate reservoirs at the state-of-the-art Alberta Energy Regulator Core Research Centre in Calgary. In sum, the meeting will have combined more than fifty technical oral and poster presentations, six field trips, and subsurface reservoir rock over five days. Of course, the true success of the meeting is through the participation of delegates-debating ideas, asking questions, sharing experiences, and challenging conventional approaches. We look forward to hearing tales of Eric and how he influenced and inspired folks and the science, and welcome you all to the inaugural Mountjoy meeting.

A re-evaluation of a fractured carbonate reservoir from the Perth Basin, Western Australia (original) (raw)

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