Seismic exploration planning considerations

 
In an optimum  Hydraulic fracturing  program planning, the four geologic factors to consider: brittle, closure stress, Proppant  particle size distribution and volume. The first two factors can be assessed based on the familiar concepts such as Young's modulus and Poisson's ratio of existing wells, which stems from inversion of seismic data.
 
Brittleness is relatively simple, there is not introduced. In the case of exploration, it was found, Second White Speckled Shale Colorado shale units are most vulnerable part of the group, closure stress is defined as not having the proper position  ceramic proppant  fracturing stress of which the effective closure.
 
Wide-azimuth-D seismic data to allow assessment of all major stress, primarily through the use of a simplified Hooke's law and linear slip theory. In addition, you also need to consider is that the well pressure must first overcome the rocks around the borehole formed hoop stress. Hoop stress in the rock near the wall of the additional shear stress, which is mainly a result of drilling. Once the assessment of seismic data from the main stress has been mastered, the hoop stress can also be calculated.
 
Obviously, the original rock stress is to control the hydraulic fracturing of the most important factors. As rock geotechnical testing to withstand long-term deformation, static modulus of stress-strain relationship can be assessed according to the slope. Thus, the modulus of the relevant hydraulic fracturing is most likely static modulus, as hydraulic fracturing rock fracturing takes some time to build up the required stress.
 
Situ stress can be assessed based on seismic data. If it is assumed subsurface rock mechanics constrained by horizontal direction, that is, the level of strain is their natural state zero, the rock is undergoing elastic deformation, so these rocks situ stress can be assessed according to the elastic deformation of the information.
 
Elasticity information based on seismic data inversion is offset by the amplitude of the joint can be exported, and in-situ stress can be anywhere seismic waveform is assumed that the seismic waves from a larger angle (> 40 °) rock reflection, thus, this is the width corner, where the use of wide-azimuth seismic.
 
How to determine reservoir fracturing is one of the most useful parameters poor level of stress ratio (DHSR). In general, the level of differential stress ratio is low, then for reservoir fracturing is the most appropriate, when the horizontal differential stress is high, the hydraulic fracturing will tend to occur when the surface does not intersect with the maximum horizontal stress parallel , the fracturing is formed parallel with it helps. However, with low levels of differential stress ratio, hydraulic fracturing caused by the fracture will tend to spread out in various parallel to the direction and interactive. This multi-directional fracture network provides access to the reservoir of hydrocarbons better way.
 
Hydraulic fracturing of the best scenes that occurred with high brittleness, and with low levels of differential stress ratio (DHSR) meet. Cross plots of these assessments can be shown that the area suitable for the formation of the fracture network. In Colorado group Second White Speckled Shale, the results of the application which cross plot in Figures 3 and 4 below. Intersection graph Strip and cut-off point is controlled as well as to optimize field development. Those low differential stress ratio and high Young's modulus (brittle) (shown in green part) of the area is limited to a small range has exploration. These areas should be the first goal of drilling to further significantly improve production and increase net present value.
 
Optimal hydraulic fracturing mark in a very short distance changes, for example, the figure of the north-central 14-13 wells west shows good from hydraulic fracturing hydraulic fracturing bad area to the change in the region, at a distance less than 200 meters (656 feet), much shorter than most of these shale in the length of the horizontal wells. The results also show that most of the Second White Speckled Shale will vary with parallel cracks fracturing.
 From wide-angle, wide-azimuth seismic data there are numerous signs can assist hydraulic fracturing program. It should be noted that the method is applicable to any hydraulic fracturing rock to be considered, but stress or Geomechanics is still a problem. Borehole seismic data should be used to infer information on inter-well area.
 
This analysis can be used in the absence of seismic velocity measurements and assumptions petrophysical relationship information when well implemented. Once the main stress is calm as other useful hoop stress stress assessment can be used to predict how oil and gas well drilling operations that. This is the basis for wide-azimuth three-dimensional seismic data evaluation lot about stress and rock properties information.