TABLE OF CONTENTS One of the most important goals of modeling is to reduce the risk associated with making decisions in an environment where knowledge is limited. The validity of data used in the decision-making process depends on the measurement technique used to obtain the data and the appropriate scale of applicability of the technique. Data validity provides information about risk. The integration of scale-dependent data into a cohesive reservoir description can reduce the risk of decision-making. This chapter introduces the concept of scale and discusses Giga Scale information.
We can obtain a sense of just how well we understand the reservoir by considering the fraction of reservoir area sampled by different techniques. As an example, suppose we want to find the size of the area sampled by a wellbore that has a 6-in. radius. If we assume the area is circular, we can calculate the area as ? r 2 where r is the sampled radius. The area sampled by a 6-in. radius wellbore is less than a square foot. To determine the fraction of area sampled, we normalize the sampled area with respect to the drainage area of a well. If we assume the drainage area of the well is a modest five acres, the drainage area is 218,000 sq. ft. What fraction of the drainage area is directly sampled by the wellbore? The fraction of the area sampled by the well is three to four parts in a million. This is a tiny...
