Hydraulic fracturing is one of major methods of wellbore completion during tight oil field development. Resulting fracture permeability may significantly decline in time for some reasons. The wellbore productivity decreases as a result. One of major ways to restore the permeability of fracture is repeated hydraulic fracturing. This operation under definitive conditions may result not in expected fracture permeable properties renewal but in second hydraulic fracture initiation. The second hydraulic fracture as a rule lies in nearly perpendicular direction with respect to the first one. The physical fundamentals of fracture reorientation of second hydraulic fracturing operation are described in this paper. This phenomenon arises only on working production wells completed with fracture fixed by proppant. The reorientation phenomenon allows using fundamentally new way to find wells – candidates for the second hydraulic fracturing operation. The essential advantage of using this new way is in involvement of resources from higher residual content of hydrocarbons and also in a lack of new wellbore drilling necessity. The major risk in using the effect of fracture reorientation is in the possible breakthrough of the water injection front and related increasing of oil production watering. Using the phenomenon described is possible only by using geomechanical instruments of formation stress-strain state monitoring. In the paper we also show some examples of wells with reoriented fractures. The confirmation of the effect was given both using direct measurement with cross-dipole acoustic logging and indirect way using watering change analysis of oil production during a long-time.
References
1. Roussel P.R., Sharma M.M., Quantifying transient effects in altered-stress refracturing of vertical wells, SPE 119522, 2009.
2. Fedorov A.I., Davletova A.R., Kolonskikh A.V., Toropov K.V., Justification of the necessity to consider the effects of changes in the formation stress state in the low permeability reservoirs development (In Russ.), Nauchno-tekhnicheskiy vestnik OAO “NK “Rosneft'”, 2013, no. 2, pp. 25–29.
3. Latypov I.D., Fedorov A.I., Nikitin A.N., Research of reorientation refracturing (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2013, no. 10, pp. 74–78.
4. Elbel J.L., Mack M.G., Refracturing: Observations and theories, SPE 25464, 1993.
5. Li P., Song Z., Study on reorientation mechanism of refracturing in Ordos Basin, SPE 104260, 2006.
6. Economides M.J., Nolte K.G., Reservoir stimulation, Third edition, Wiley, NY and Chichester, 2000, 750 p.
7. Liu H. et al., Evaluation of refracture reorientation in both laboratory and field scales, SPE 112445, 2008.
8. Fedorov A.I., Davletova A.R., Reservoir stress state simulator for determining of fracture growth direction (In Russ.), Geofizicheskie issledovaniya, 2014, V. 15, no. 1, pp. 15–26.
