**6.1 Estimation of differential stress: geomechanics vs. surface drilling data**

The first result of the reservoir geomechanics approach [11] is the differential stress (**Figure 6**) which can be used as shown in Paryani et al. [18] to geoengineer completions. The advantage of using differential stress for geoengineering completions is the ability to consider the complex geology beyond the wellbore. In other words, well-centric approaches such as the one relying entirely on using a reference log derived from surface drilling data, are approximations that work only if the geology is not highly variable around the considered well. When the geology is variable with significant variability of the geomechanical properties, natural fractures, and pore pressure, then the best approach is to use the derived 3D models as input in the reservoir geomechanics approach [11] to estimate the differential stress.

 **Figure 6** shows a two well pad where faults (**Figure 6A**) were interpreted from multiple wells and used as input in the geomechanical approach [11] to compute the differential stress (**Figure 6B**). Since the analysis of surface drilling data was available in both wells, the differential stress was also estimated by using only that limited information. The computed differential stress from surface drilling data (**Figure 7**, right track) is compared to the one derived from the reservoir geomechanical simulation (**Figure 7**, left track) extracted along the wellbore from the differential stress distribution shown in **Figure 6B**. This comparison shows very strong similarities between the differential stress derived from full reservoir geomechanics (**Figure 7**, left track) with the one derived from the well centric approach based

**Figure 6.** 

*(A) Interpreted faults used as input in the reservoir geomechanics that estimates (B) the differential stress and the lateral stress gradients needed to geoengineer the stages.* 

*Surface Drilling Data for Constrained Hydraulic Fracturing and Fast Reservoir Simulation… DOI: http://dx.doi.org/10.5772/intechopen.84759* 

**Figure 7.** 

*(Left) Differential stress derived from reservoir geomechanics results shown in* **Figure 6B***. (Right) differential stress derived from a well centric approach using only surface drilling data***.** 

only on surface drilling data (**Figure 7**, right track). Both curves indicate the same zones for high differential stress zones where engineered completions are required to overcome earth resistance to hydraulic fracturing. The engineered completion could adjust the pumping parameters, stage length and number of clusters according to the derived differential stress with the objective of pumping bigger stage lengths in areas of low differential stress and vice versa. Areas of low differential stress will promote complex fracturing whereas areas of high differential stresses will result in planar hydraulic fractures with lower cluster efficiency as shown in **Figure 8**. The resulting engineered completion can be derived within a few hours of the well reaching Total Depth (TD) which illustrates the benefits of using surface drilling data if no other information is available.
