Study of the problem of optimization of bottomhole pressure for fractured-porous reservoirs

UDK: 622.276.1/.4.001
DOI: 10.24887/0028-2448-2017-10-94-97
Key words: optimal bottomhole pressure, limited bottomhole pressure, fractured-porous reservoir, flow simulation, inverse problem, producing well, injection well
Authors: V.A. Iktissanov, I.F. Bobb (GeoExpert Service OOO, RF, Moscow), B.G. Ganiev (Tatneft PJSC, RF, Almetyevsk)

Determination of optimal bottomhole pressures of wells in a field or in a field area has been the subject of research for many specialists. Earlier works were focused on determination of limited bottomhole pressures, because it was generally accepted that limited bottomhole pressures ensure the most efficient and effective development of reserves. However, a more rigorous solution can be achieved through application of flow simulation and inverse modeling methods. Some approaches to solve this problem are discussed in this paper. To find optimal bottomhole pressure we have created models with different reservoir characteristics and fluid properties. The calculation results were analyzed considering specific reservoir conditions. We have revealed some principles that can be applied to improve performance of real oil and gas fields. The paper discusses the issues related to determination of pressure in fractured-porous reservoirs. It is common knowledge that these reservoirs are characterized by low oil recovery factor and low cumulative oil production. The research results show that the choice of optimal bottomhole pressure in fractured-porous reservoirs is largely dictated by presence or absence of gas-cut fluid flow. In case the bubble point pressure is close to the initial reservoir pressure, optimal bottomhole pressures differ significantly from limited bottomhole pressures and, thus, should be calculated both for production and injection wells, yet, within the range of limited bottomhole pressures. In case the bubble point pressure is lower than the initial reservoir pressure, limited bottomhole pressure is the right choice for production wells. As a side note, the highest cumulative production and NPV in fractured-porous reservoirs can be attained if reserves are produced by natural flow up to the point the reservoir pressure equals the bubble point pressure, so, water flooding to maintain formation energy should not be started until the reservoir is in solution gas drive. The revealed principles can be applied to improve production rates, cumulative production, and NPV of carbonate reservoirs.

References

1. Muslimov R.Kh., The development of oil field development systems on the pages of the “Neftyanoe khozyaystvo” journal (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2005, no. 9, pp. 57-63.

2. Shakhverdiev A.Kh., Sistemnaya optimizatsiya protsessa dorazrabotki neftyanykh mestorozhdeniy (System optimization of process of oilfield redevelopment): thesis of doctor of technical science, Moscow, 2001.

3. Lysenko V.D., Grayfer V.I., Ratsional'naya razrabotka neftyanykh mestorozhdeniy (Rational development of oil fields), Moscow: Nedra Publ., 2005, 607 p.

4. Iktisanov V.A., Patterns control the development of oil fields using optimization bottom-hole pressures for the porous collector (In Russ.), Burenie i neft', 2017, no. 3, pp. 14-18.

5. Zheltov Yu.P., Deformatsiya gornykh porod (Deformation of rocks), Moscow: Nedra Publ., 1966, 198 p.

6. Golf-Racht T., Fundamentals of fractured reservoir engineering, Amsterdam, New York: Elsevier, 1982.

 

Determination of optimal bottomhole pressures of wells in a field or in a field area has been the subject of research for many specialists. Earlier works were focused on determination of limited bottomhole pressures, because it was generally accepted that limited bottomhole pressures ensure the most efficient and effective development of reserves. However, a more rigorous solution can be achieved through application of flow simulation and inverse modeling methods. Some approaches to solve this problem are discussed in this paper. To find optimal bottomhole pressure we have created models with different reservoir characteristics and fluid properties. The calculation results were analyzed considering specific reservoir conditions. We have revealed some principles that can be applied to improve performance of real oil and gas fields. The paper discusses the issues related to determination of pressure in fractured-porous reservoirs. It is common knowledge that these reservoirs are characterized by low oil recovery factor and low cumulative oil production. The research results show that the choice of optimal bottomhole pressure in fractured-porous reservoirs is largely dictated by presence or absence of gas-cut fluid flow. In case the bubble point pressure is close to the initial reservoir pressure, optimal bottomhole pressures differ significantly from limited bottomhole pressures and, thus, should be calculated both for production and injection wells, yet, within the range of limited bottomhole pressures. In case the bubble point pressure is lower than the initial reservoir pressure, limited bottomhole pressure is the right choice for production wells. As a side note, the highest cumulative production and NPV in fractured-porous reservoirs can be attained if reserves are produced by natural flow up to the point the reservoir pressure equals the bubble point pressure, so, water flooding to maintain formation energy should not be started until the reservoir is in solution gas drive. The revealed principles can be applied to improve production rates, cumulative production, and NPV of carbonate reservoirs.

References

1. Muslimov R.Kh., The development of oil field development systems on the pages of the “Neftyanoe khozyaystvo” journal (In Russ.), Neftyanoe khozyaystvo = Oil Industry, 2005, no. 9, pp. 57-63.

2. Shakhverdiev A.Kh., Sistemnaya optimizatsiya protsessa dorazrabotki neftyanykh mestorozhdeniy (System optimization of process of oilfield redevelopment): thesis of doctor of technical science, Moscow, 2001.

3. Lysenko V.D., Grayfer V.I., Ratsional'naya razrabotka neftyanykh mestorozhdeniy (Rational development of oil fields), Moscow: Nedra Publ., 2005, 607 p.

4. Iktisanov V.A., Patterns control the development of oil fields using optimization bottom-hole pressures for the porous collector (In Russ.), Burenie i neft', 2017, no. 3, pp. 14-18.

5. Zheltov Yu.P., Deformatsiya gornykh porod (Deformation of rocks), Moscow: Nedra Publ., 1966, 198 p.

6. Golf-Racht T., Fundamentals of fractured reservoir engineering, Amsterdam, New York: Elsevier, 1982.

 



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