CO2 Huff 'n' Puff Revives Shallow Light-Oil-Depleted Reservoirs

Abstract

Cyclic CO 2 huff 'n' puff process in diverse reservoir conditions, such as immiscible, near-miscible, and miscible, has been tested in the laboratory and applied in the fields as a viable secondary or tertiary means to recover the residual oil in water flooded reservoirs or pressure depleted reservoirs. Recently, petroleum operators have shown increasingly interest in taking CO 2 huff 'n' puff process as a preferred option to extract light oil in low-pressure and low-permeability reservoirs.In this paper, experimental results from a series of coreflood tests are presented and operation strategies for cyclic CO 2 injection are optimized to maximize the light oil recovery factor in a low-permeability reservoir with low original reservoir pressure and while, minimize CO 2 utilization. 6 cyclic coreflood tests, 20 cycles in total, are conducted in a 973 mm-long composite core with an average porosity of 9.6% and an average permeability of 2.3mD. The reservoir pressure is 12.9MPa, far below the measured MMP value of 23MPa, which indicates that the reservoir has no sufficient energy support to do primary production. The impacts of primary operational parameters, such as slug size, injection pressure, chasing gas (N 2 ) and CO 2 injection rate on the performance have been investigated.It is concluded that, on the basis of experimental data, 0.1PV seems to be an optimal slug size for the first cycle, with a cycle recovery factor as high as 14.52% when reservoir pressure depleted to 8MPa. The recovery factor is suggested to be sensitive to the maximum pressure and the maximum pressure should be built up to as high as formation permits. In the following cycles, injecting N 2 as chasing gas after CO 2 injection seems to improve the cycle performance significantly and concurrently reduce the CO 2 utilization. The optimal operation should have three cycles and the ultimate recovery factor for these three cycles could reach above 30%. The findings of this paper extend the understanding of cyclic CO 2 operation and may be employed as technique reference for cyclic CO 2 process operations in low-pressure and low-permeability closed boundary reservoirs.

Enhanced Heavy Oil Recovery on Depleted Long Core System by CH4 and CO2

“…Huff and puff processes have been studied in the field and laboratory as well as by reservoir simulation by many investigators (Bardon et al, 1991;Haskin and Alston, 1989;Palmer et al, 1986;Simpson, 1988). Torabi and Asghari (2004) performed a CO 2 huff and puff process in fractured porous media and high recovery rate of 48-94% were obtained.…”

Modeling, analysis, and screening of cyclic pressure pulsing with nitrogen in hydraulically fractured wells

“…Moreover, they found that soaking mainly affects the peak production rate after injection. Later, cyclic injection of carbon dioxide was utilized for heavy oil in California (Sankur and Emanuel 1983), Arkansas (Khatib et al 1981), and Turkey (Bardon et al 1986), and for light and medium types of oil in Kentucky (Bardon et al 1994), Texas (Haskin and Alston 1989), and Louisiana (Monger and Coma 1988). In the 1990s and 2000s, nitrogen and mixtures with nitrogen were proposed and successfully applied (Shayegi et al 1996;Miller and Gaudin 2000).…”

Numerical Simulation of CO2 Gas Microbubble of Foamy Oil

“…The EOR by CO2 foaming with using huff-and-puff process has been applied either light oil [1,2] or heavy oil [3,4]. The procedure of huff-and-puff method is the repeating of injection and production which is called pressurization and depressurization or carbonation and liberation [4].…”