Creating Variance Cube from Seismic Data and Converting to Transmissibility Multiplier Pattern to Assist History Match

Abstract

Abstract This paper demonstrates how to utilize seismic data to create a variance cube with different values and convert it into a transmissibility multiplier pattern to assist the history match in dynamic simulation. Lateral variations of the seismic signal can be related to various reasons, such as faults respectively associated fault damage zones and sedimentological bodies like channel features. Dissimilarities within the seismic data can be emphasized by calculating a variance attribute. The different value ranges within the variance cube can in the chosen examples be associated to the fault plane itself and different intensities of fault related rock alterations or channel characteristics, e.g. erosional planes. These features can result in improved or reduced lateral transmissibility as poor or good rock properties coincide with poor or good transmissibility for fluid flow. The variance value patterns can be analyzed and categorized according to the discrete value ranges. Then the categories are converted to reference numbers, e.g. variance reference number 1 represents a good transmissibility (e.g. a channel body), 2 represents reasonable and 4 represents the poorest class (e.g. an intense faulted zone). Subsequently the variance reference number is converted to a transmissibility multiplier value. During the history match process, these multipliers are adjusted in order to improve the history match. The advantage of this approach is that it does not only change the transmissibility multiplier in one cell, but changes the transmissibility multiplier value of each cell that belongs to one type of rock quality (one variance reference number or one transmissibility group) in one calculation. This is especially useful where there is limited history data and the variance data indicates similar patterns throughout the variance cube. This method can speed up the history matching as it is a batch change of transmissibility multipliers, similar to the fault transmissibility multiplier method in ECLIPSE but with a wider application. In a case study a comparison was conducted with using the variance cube / transmissibility multiplier patterns and confirmed the method workable. In conclusion using the variance cube to create transmissibility multiplier patterns is an efficient way to assist and improve history matching, especially in fields with limited well control. This paper presents a new way of creating transmissibility multipliers based on seismic data (variance attribute) and assisting and improving the history match process