# 1.4 Input data

Every reservoir modeling project starts with the definition of the extent of the model and what data should be included in the modeling (Figure 1). This task seems straightforward and yet many modeling projects don’t meet their deadlines because this phase didn’t involve enough the whole team. Figure 2 gives an example of the type of problems any team might face.

A company’s lease covers three sections (Figure 2A and C, orange squares). Two horizontal wells are to be drilled soon (H1 and H2) and management asked for a flow simulation model to be run around those future wells. To do so, the engineers ask their geologist to build a reservoir model around those two horizontal wells. Engineers need the model to be ready in one month. The geologist agrees on their deadline and gets started. Data are available on all the vertical wells (blue triangles) and there is no seismic. The geologist decides to model the reservoir within the red polygon (Figure 2A). Her choice is motivated by two things. Firstly, there is no need to include the whole lease as only the zone around the future horizontal wells is of interest. Secondly, the polygon includes the well W1, even if it is outside the company’s lease, to get a better control during the interpolation of the facies and the petrophysics on the North-West of the well H1. On the contrary, the vertical wells W2 and W3 located South of the lease are excluded. W2 is considered too far to be relevant while the South-East corner of the picked polygon already contains a vertical well, making W3 redundant.

The reservoir modeling moves forward and the geologist delivers her model to the engineers on time. To her surprise, the engineers reject it: it doesn’t include the horizontal well H3 located East of the lease. While not needed to model the rocks around H1 and H2, and so rightfully ignored for the geomodeling, this well is producing and to the engineers it was obvious that they needed this well in the model for their flow simulation. As it was obvious to them, they assumed it was obvious for the geologist, so they didn’t see the point of saying it aloud during the kick-off meeting.

Our geologist goes back to her office, adjust the extent of the geomodel as needed (Figure 2C, green polygon) and she delivers an updated geomodel a month later, completely missing the engineers’ deadline.

Years of consulting has shown that this type of problem happens often: a misunderstanding in the scope of work is spotted only at the end of the project when the model is reviewed. It is then necessary to redo everything. The issue is a lack of communication in the team at the beginning of the project. In my example (Figure 2B), engineers didn’t spend time – or were not asked to spend time – in defining which data were needed. Had they been ((Figure 2D), engineers would have had a chance to mention the well H3 and the misunderstanding would have been lifted before causing any damage.