Chaunoy Formation

Worden R. H., Coleman M. L., and Matray J. M. (1999) Basin scale evolution of formation waters a diagenetic and formation water study of the Triassic Chaunoy Formation, Paris Basin. Geochim. Cosmochim. Acta 63, 2513-2528. 

Carbonate cement in the Triassic Chaunoy Formation of the Paris Basin distribution and effect on flow properties... 

Table 3. Average petrographic data from the Chaunoy Formation sandbodies. Twenty-two samples were examined petrographically. The figures illustrate the importance of dolomite in the Chaunoy Formation...

Fig. 5. Wireline sonic transit time, density and neutron density through the cored portion of the Chaunoy Formation.

Fig. 9. The non-uniform distribution of dolomite and porosity in the Chaunoy Formation sandbodies. The numbers refer to the sandbodies numbered in Fig. 8. (A) Dolomite is preferentially concentrated in the top quarter of each sandbody. (B) Conversely, porosity is concentrated in the middle two quarters of each sandbody.

Effect of dolomite cement upon the reservoir properties of the Chaunoy Formation sandstone... 

Dolomite cement is generally concentrated at the tops of sandbodies in the Chaunoy Formation (Figs 7 and 9). There are several potential generic controls on dolomite distribution patterns (Fig. 10). 

Petrography and, more importantly, wireline log data have shown that dolomite cement is not uniformly distributed throughout the sandstones within the Chaunoy Formation. Rather, dolomite cement is localized within the top portions of individual sandstone units. 

Reservoir quality in the Chaunoy Formation is a function not just of depositional facies but also of localized cement distribution. Building a reservoir model using primary sandbody architecture alone is insufficient to correctly describe reservoir quality. 

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