Summary
Refracturing is used in many producing wells to improve well productivity, which falls over time. Well rate/pressure performance analysis indicates that in some cases a significant improvement of well productivity is observed after refracturing. Fracture reorientation is a possible reason why well productivity improves. It is important to run a forecast of fracture reorientation after refracturing. Completing this task will help develop an approach to a better selection of candidate wells for refracturing.
This paper shows results of numerical modeling of well rate and pressure performance before and after refracturing for cases when properties of the "old" fracture improved and for a case of fracture reorientation after hydraulic fracturing (HF), i.e., for two (the "old" one and the "new" one) perpendicular fractures. Results of numerical modeling made it possible to estimate the contribution that the improvement/recovery of the "old" fracture properties make into the well inflow as well as the contribution resulting from the existence of two fractures. Further, the production pressure analysis of field data for wells where repeated HF jobs were performed was made. The occurrence of fracture reorientation in all considered examples was checked in the geomechanical module. The analysis of the impact, which different reservoir values, Yung module have upon the possibility to redirect the fracture during refracturing, was performed in the geomechanical module, too.
The development increasingly involves reservoirs with low and ultra-low permeability reservoir. "Traditional" welltest analysis technologies in such reservoirs lose their efficiency (Davletbaev A.Y., Zhylko E. Y. etc. 2015, Loznyuk O.A. etc. 2015) as they require long-time shut-in (about 1 month and more), which causes huge losses in production (Davletbaev A.Y., Islamov R. R etc. 2015). In such conditions, analysis of usual operation data analysis and decline analysis become relevant (Arps J.J. 1945, Fetkovich M.J. 1980, Ilk D., Blassingame T.A. 2013, Doublet D.E. etc. 1994). This method has a lot of limitations, in particular, it is necessary to know the value of the reservoir pressure at the moment of the reservoir operation for interpretation, which is not always possible in the conditions of the operation and maintenance phase. The present work offers the method permitting to increase the informational content of the decline analysis, as well as to determine the value of initial reservoir pressure by combining «short» build-up welltest analysis with decline analysis in the operating well.
Представлены результаты моделирования фильтрации в элементе линейной системы разработки с трещинами гидроразрыва пласта. Изучено влияние коэффициента пьезопроводности и расчлененности пласта на распределение давления между скважинами. Решение задачи было получено методом функции Грина, также выполнена реализация задачи в ПК «РН-КИМ» для оценки эффективности системы поддержания пластового давления (ППД).
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