scholarly journals A predictive model for the wettability of chalk

2020 ◽  
Vol 2 (10) ◽  
Author(s):  
Meysam Nourani ◽  
Niels Hemmingsen Schovsbo ◽  
Ashkan Jahanbani Ghahfarokhi ◽  
Carsten Møller Nielsen ◽  
Lykourgos Sigalas ◽  
...  

Abstract Wettability is usually measured in special core analyses of limited plug samples according to typically costly and time-consuming procedures. For comparative purposes, wettability is considered an index. The two most frequently used wettability indices are the Amott–Harvey wettability index and the U.S. Bureau of Mines (USBM) index. The Amott–Harvey wettability index is linked to imbibition characteristics and the USBM index is associated with the area under capillary pressure curves. To provide a fast analytical method, a mathematical model for predicting the wettability of chalk is presented. The model is calibrated using experimental wettability data and subsequently applied to two wells in Danish chalk oil fields in the North Sea and to outcrop chalk samples. The model supplements traditional labor-intensive laboratory measurements and predicts water wettability variations with depth by modeling both depth and porosity dependencies; in addition, it provides estimates of the effects of the aging time and displacement temperature of chalk wettability measurements in the laboratory.

CONVERSAZIONES were held this year on 6 May and 24 June. At the first conversazione twenty-four exhibits and a film were shown. Dr P. E. Kent, F.R.S., and Mr P. J. Walmsley of The British Petroleum Company Limited arranged an exhibit demonstrating the latest progress in the exploration for hydrocarbons in the North Sea. The established gas fields and the recently discovered oil fields were shown on maps together with sections which illustrated their structure. Seismic sections and geological interpretations were exhibited to show the type of information being obtained in the North Sea and the structural complexities which arise. A scale model of one of the semi-submersible drilling outfits used in North Sea exploration was on display together with a sample of British North Sea oil.


1990 ◽  
Author(s):  
A.M. Thompson ◽  
G.A.A.H. Holmes ◽  
P.J. Benstead

1978 ◽  
Author(s):  
Alexander George Kemp ◽  
David Crichton
Keyword(s):  

A mathematical model is used to reproduce tidal and surge motion in the Thames Estuary and the Southern Bight of the North Sea. The model is based on a numerical finite-difference solution of the nonlinear hydrodynamical equations representing motion in the area. The equations are nonlinear in so far as they include quadratic bottom friction and allow for time variations in the total depth of water; the inclusion of advective terms is limited to the river. Solution of the one-dimensional equations for the river and the two-dimensional equations for the sea takes place within a single computational array. The scheme for calculating motion in the sea is similar to that developed by Heaps (1969), and the scheme for the river was developed by Rossiter & Lennon (1965). Tidal and surge motion within the model are reproduced by specifying the initial tidal contours of the sea, the external influences of surge and tidal oscillation along the open sea boundaries, and wind stresses over the sea surface. Computations have been concerned with generating lunar tidal oscillations for the construction of an M2 co-tidal chart, and investigating the interaction between tides and surges, in this region of shallow waters. The investigation of interaction involved calculating the sea’s response to the separate and combined effects of tidal and meteorological forces, whence the effects of a tide on a surge were deduced, possibly for the first time at offshore locations. Computed interaction phenomena for the period of a severe storm surge, 15 to 17 February 1962, were found to accord with the results of Proudman (19550, b, J957) and Rossiter (1961). Agreement between computed sea-level disturbances and actually recorded disturbances for this surge period revealed that the model has good potential for simulating sea level disturbances which occur in nature.


Author(s):  
D. J. Gunn ◽  
J. McManus ◽  
O. Yenigun

SynopsisIn a mathematical model of the Tay (Gunn & Yenigun 1987) based upon the Local Integral Method (Gunn & Yenigun 1985), tidal levels at the seaward boundaries and velocities at landward boundaries are used in setting boundary conditions, so that validation studies are mainly based upon changes in internal tidal levels, and comparison between computed and measured velocities within the modelled region. The comparisons of tidal levels within this estuary over a 5.0 m tide showed agreement with overall values from Buddon Ness to the rail bridge, but within the overall agreement there were significant differences in the immediate vicinity of the road bridge. Velocities predicted within the estuary have been compared with measurements provided by a number of surveys in the period from 1972-78. The agreement between experiment and prediction was good in the central and western regions of the model, but the comparison between measurement and prediction was less good near the eastern boundaries. The principal reason for poorer agreement in the east was the difficulty in setting boundary conditions at the open sea extremes of the model. The most satisfactory way of improving the model near the open sea boundaries would be to link the model for the Tay with a model for velocity and level in the North Sea.


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