To control the uncertainties in specific reservoirs with specific development objectives, different fit-for-purpose services while drilling should be employed to achieve the necessary 2D reservoir description along the well trajectory for reservoir evaluation, geosteering, and further plan optimization. However, the current accuracy of reservoir description with specific services while drilling can only be evaluated qualitatively. Under the current digital oilfield environment, the reservoir-profile-update rate (RPUR) is introduced as a key quantitative indicator to evaluate the accuracy of 2D reservoir description and the degree to which a 2D reservoir profile is updated with specific services while drilling.

Updating a reservoir profile involves updating its boundaries and layers. The updating range and probability greatly depend on the depth of detection (DOD) and resolution of the selected services. A deeper DOD and higher resolution results in more boundaries and interlayer areas detected with higher certainty, and a higher profile update degree with a higher probability. Conversely, the opposite is true: a lower DOD and lower resolution results in fewer boundaries and fewer interlayer areas detected, and a lower degree of certainty. RPUR is defined as the average of the boundary-update rate and the layer's property-update rate.

In this paper, multiple examples are presented demonstrating the advantages of different services for the effective reservoir description in specific reservoirs, which were also quantitatively evaluated by an RPUR factor. RPUR and quantitative reservoir description present the quantitative advantages and feasibility of different services while drilling for specific objectives. The current RPUR concept is only a prototype with simplified factor and standard considered. More details should be input to refine this concept for more applicable reservoirs and situations.

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