1. Field of the Invention
The invention herein relates to forming models of subsurface earth formations based on data obtained from wells being drilled in those formations.
2. Description of the Related Art
With increased competition in the energy market, oil companies face a daunting task of improving accuracy while reducing cycle time. Technologies in horizontal drilling, real time monitoring, and reservoir modeling have advanced significantly during the last few years. There are still, however, conceptual gaps in knowledge of the actual subsurface structure in well plans by geoscientists and engineers for a well to be drilled.
Typically, the well plan is an earth model based on best available information from surveys, well logs and other reservoir techniques. The interest is to locate a well at particular locations in a formation of interest for optimum production. A considerable number of wells currently being drilled are drilled horizontally through a formation or reservoir of hydrocarbon interest. The objective in such a well is for the well base to have a suitable length or exposure of extent, usually expressed in terms of reservoir feet, in the formation.
In the event that the actual subsurface formations or stratigraphy differ from the well plan, the well bore may be located in the reservoir at a position where less reservoir feet of extent in the reservoir are obtained than were planned. In some instances, even with sophisticated well plans, the actual subsurface formation may differ sufficiently from the plan model so that the well bore does not contact the reservoir of interest for any significant extent.
There have been techniques for forming revised or updated models based on well data. However, so far as is known, conventional techniques to form revised or updated models have taken days or weeks. Thus, the revised data or well model was not available until long after drilling operations had passed the proper location for corrections to be made in steering of the drill bit to better locate the well in the reservoir of interest.