Some peculiarities of pore space colmatation process in stress heterogeneous clayey reservoirs

UDK: 622.279.031.011.43
DOI: 10.24887/0028-2448-2017-8-72-74
Key words: injection, filtration, clay particles, sedimentation, permeability
Authors: A.N. Garaeva, E.A. Korolev, M.G. Khramchenkov (Kazan (Volga Region) Federal University, RF, Kazan)

The work is devoted to the analysis of the features of the process of deposition of the pore space of rocks (colmatation process) in an overall mathematical description, that is, taking into account the change in the stress-strain state of the rocks. The most relevant is the analysis to determine the reasons for the decrease in the filtration properties of oil reservoirs during oil production, which is accompanied by the injection of water into the reservoir. It is known that in a number of cases the injection of water into the reservoir results in a decreasing in the filtration properties of the some reservoir regions adjacent to the injection wells, and the reasons for this decrease can’t be explained by a violation of the injection technology. The paper considers one of the possible mechanisms for changing the filtration properties of oil reservoirs due to the colmatation of pore space by clay particles. Particles can come along with water pumped into the injection wells, carried out together with a part of the drilling mud or mobilized in the reservoir itself due to erosion processes in the zones with an increased value of the actual filtration rate. A mathematical description of the colmatation process of the porous space of the reservoir is constructed with allowance for the change in its stress-strain state. Accounting for changes in the stress-strain state of the reservoir opens up new opportunities for analyzing the features of the course of erosion-and-colmatation processes during oil production. Calculations for the model are supplemented by experimental studies. Experimental studies were carried out on bulk samples of a porous medium with a change in the permeability coefficient when injecting a solution containing suspended clay particles. In addition, the experimental data of other authors were used. The constructed mathematical model of the process was verified by comparing the results of calculations on the model with the obtained experimental data; as a result, a good correspondence of the calculated and experimental data was obtained.

References

1. Maksimenko A.A., Mikromekhanicheskiy analiz techeniya nen'yutonovskikh zhidkostey i vzvesey v poristoy srede (Micromechanical analysis of the flow of non-Newtonian fluids and slurries in a porous medium): thesis of candidate of physical and mathematical sciences, Moscow, 2001.

2. Ryzhikov N.I., Eksperimental'noe issledovanie dinamiki zakhvata chastits i izmeneniya pronitsaemosti pri fil'tratsii suspenzii cherez poristuyu sredu (Experimental study of the dynamics of particle capture and permeability changes during filtration of a suspension through a porous medium): thesis of candidate of physical and mathematical sciences, Moscow, 2014.

3. Jaeger J.C., Zimmerman R.W., Fundamentals of rock mechanics, 4th ed. Oxford, Wiley, 2007.

4. Khramchenkov M., Khramchenkov E., A new approach to obtain rheological relations for saturated porous media, International Journal of Rock Mechanics & Mining Sciences, 2014, V. 72, pp. 49–53.

5. Dimov C.V., Kuznetsov V.V., Rudyak V.Ya., Tropin N.M., Experimental investigation of microsuspension filtration in a highly-permeable porous medium (In Russ.), Izvestiya Rossiyskoy akademii nauk. Mekhanikazhidkosti i gaza = Fluid Dynamics, 2012, no. 2, pp. 47–56.

6. Nikolaevskiy N.V., Geomechanics and fluid dynamics, Dordrecht: Kluwer Academic Publishers, 1996.

7. Coussy O., Poromechanics, London: Wiley, 2004.

The work is devoted to the analysis of the features of the process of deposition of the pore space of rocks (colmatation process) in an overall mathematical description, that is, taking into account the change in the stress-strain state of the rocks. The most relevant is the analysis to determine the reasons for the decrease in the filtration properties of oil reservoirs during oil production, which is accompanied by the injection of water into the reservoir. It is known that in a number of cases the injection of water into the reservoir results in a decreasing in the filtration properties of the some reservoir regions adjacent to the injection wells, and the reasons for this decrease can’t be explained by a violation of the injection technology. The paper considers one of the possible mechanisms for changing the filtration properties of oil reservoirs due to the colmatation of pore space by clay particles. Particles can come along with water pumped into the injection wells, carried out together with a part of the drilling mud or mobilized in the reservoir itself due to erosion processes in the zones with an increased value of the actual filtration rate. A mathematical description of the colmatation process of the porous space of the reservoir is constructed with allowance for the change in its stress-strain state. Accounting for changes in the stress-strain state of the reservoir opens up new opportunities for analyzing the features of the course of erosion-and-colmatation processes during oil production. Calculations for the model are supplemented by experimental studies. Experimental studies were carried out on bulk samples of a porous medium with a change in the permeability coefficient when injecting a solution containing suspended clay particles. In addition, the experimental data of other authors were used. The constructed mathematical model of the process was verified by comparing the results of calculations on the model with the obtained experimental data; as a result, a good correspondence of the calculated and experimental data was obtained.

References

1. Maksimenko A.A., Mikromekhanicheskiy analiz techeniya nen'yutonovskikh zhidkostey i vzvesey v poristoy srede (Micromechanical analysis of the flow of non-Newtonian fluids and slurries in a porous medium): thesis of candidate of physical and mathematical sciences, Moscow, 2001.

2. Ryzhikov N.I., Eksperimental'noe issledovanie dinamiki zakhvata chastits i izmeneniya pronitsaemosti pri fil'tratsii suspenzii cherez poristuyu sredu (Experimental study of the dynamics of particle capture and permeability changes during filtration of a suspension through a porous medium): thesis of candidate of physical and mathematical sciences, Moscow, 2014.

3. Jaeger J.C., Zimmerman R.W., Fundamentals of rock mechanics, 4th ed. Oxford, Wiley, 2007.

4. Khramchenkov M., Khramchenkov E., A new approach to obtain rheological relations for saturated porous media, International Journal of Rock Mechanics & Mining Sciences, 2014, V. 72, pp. 49–53.

5. Dimov C.V., Kuznetsov V.V., Rudyak V.Ya., Tropin N.M., Experimental investigation of microsuspension filtration in a highly-permeable porous medium (In Russ.), Izvestiya Rossiyskoy akademii nauk. Mekhanikazhidkosti i gaza = Fluid Dynamics, 2012, no. 2, pp. 47–56.

6. Nikolaevskiy N.V., Geomechanics and fluid dynamics, Dordrecht: Kluwer Academic Publishers, 1996.

7. Coussy O., Poromechanics, London: Wiley, 2004.



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