Waterflood management requires the optimization of hydraulic fracture placement and geomechanical models are critical for any field development. In the absence of direct stress measurements (vertical distribution and direction) the uncertainty on the geomechanical models will be high.creates the need to determine the orientation and magnitude of the least principal stress. Heterogeneity and presence of impermeable shales between producing sands complicates fracturing design and field development to maximize recovery. Permeability and permeability anisotropy at different depths are unknown variables that affect well completion and reservoir management decisions. Direction and magnitude of horizontal stresses thus is key for field development. Conventional LOT and XLOT are expensive and also are more destructive and limited to certain zones preferably at shoe. This raises the need for alternative reliable stress measurements.
A set of wireline formation evaluation tools are used for microfracturing (stress testing) at several sand and shale formations. The stress tests are performed by isolating wellbore using the dual packer module of the wireline formation tester (WFT) and creating a hydraulic fracture by injecting drilling fluid using the downhole pump. Combination of the wireline dual packer and standard probe also provides estimates of permeability and permeability anisotropy in sands. Formation microimagery and acoustic data are used before and after stress tests to obtain information on least-principal-stress direction.
Authors shows examples, which are based on the case studies of stress testing operations and analysis done in thinly laminated low permeability sands and shales in Western Siberian fields of Russia. These studies led to confirmation of the validity of the stress model in the pay zones and shales. Stress orientation analysis obtained after formation stress testing and from microimaging and sonic logs used for redefining and re-orienting the drilling pattern for flood management and optimization of hydraulic fracture placement.
Vladislav Achourov has a Masters Degree in Physics from Gubkin State University of Oil & Gas, He has acquired 8 years working experience in the Oil and Gas industry in Schlumberger. Vlad has worked with reservoir simulations and production logging and last 4 years was leading solutions approaches primarily involving formation testing, downhole sampling and well testing in Russia. He now works for Schlumberger in Norway.