A novel method of bidirectional displacement with artificial nitrogen gas cap and edge water for enhanced oil recovery: Experimental and simulation approaches

Abstract

The fault block hydrocarbon reservoirs developed by water flooding in Shengli Oilfield have entered into the period of high water cut and low oil recovery. The residual oil to be recovered is challenging by using the unidirectional water or gas displacement method in producing oil from the reservoirs because of water invasion or gas channeling. A novel method of bidirectional displacement with artificial nitrogen gas cap and edge water is presented to improve the oilfield development recovery efficiency. This novel method refers to the nitrogen gas injection at the top of the inclined reservoir and the edge water injection at the bottom of the reservoir simultaneously. The experiments of the sandpack model are performed to explain the benefits of nitrogen gas flooding and to evaluate quantitatively the production performance of the bidirectional displacement process. A numerical simulation technique based on the proposed method is employed to find out befitting reservoirs for implementation of this new novel method. The X48 inclined fault block hydrocarbon reservoir in Dongxin production area, Shengli Oilfield, is selected as the actual research block to verify the benefits of bidirectional displacement with artificial nitrogen gas cap and edge water. The results indicate that the oil recovery by bidirectional Creative Commons CC BY: This article is distributed under the terms of the Creative Commons Attribution 4.0 License (http://www.creativecommons.org/licenses/by/4.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).displacement of nitrogen gas injection in the X4841 injection well and edge water injection in the X48CXN9 injection well cooperatively is higher than that of unidirectional water flooding or gas flooding in the X4841 injection well. The oil recovery factor increases by 11.2% than that by the original water injection development in the X48CXN9 injection well. Another interesting finding in this work was that, for the oil recovery, an appropriate ratio relationship is established between the nitrogen injection rate and the water injection rate regardless of production rate.

Optimizing Oil Recovery: A Comprehensive Review of Foam Applications in Enhanced Oil Recovery.

“…Gases utilized in gas-flooding operations, including CO2, hydrocarbons, air, and N2, typically exhibit significantly lower viscosity and density than water and crude oil. This characteristic leads to gas preferentially channeling through high-permeability zones and experiencing gravity override [20,21,22,23]. Consequently, gas flooding tends to have suboptimal volumetric sweep efficiency, especially in cases of immiscible displacement where the displacing phase has lower viscosity.…”

Study on the strategy of directional excavation of residual oil at the edge of fault in highly deviated wells for sustainable development

“…At present, there are many classification methods of remaining oil, all of which are summarized according to the actual situation in different regions, and the research contents of different classification of remaining oil are also different. According to the scale of remaining oil, it can be divided into micro-scale and small-scale and large-scale and macro-scale [10]. According to the existing mode of remaining oil, remaining oil can be summarized into four types: one is the unused or basically unused remaining oil layer, the other is the plane remaining oil in the used oil layer, the third is the unused thickness remaining oil in the used oil layer, and the fourth is the micro-scale remaining oil in the flooded layer.…”

Effects Evaluation on Multiround Injection of a N2 Foam & Viscosity Reducer to Improve the Recovery of Fault-Block Heavy Oil Reservoir with Edge-Bottom Water: A Two-Dimensional Visualization Experimental Study

“…21,22 It can quickly replenish reservoir pressure and replace the remaining oil at the top due to its high position resulting from gravity differentiation. 7,23 Additionally, it increases the elastic energy, delaying the time for water to reassemble, 24,25 achieving the effect of water control and stable production. However, gas channeling is easily prone to occurring in nitrogen flooding.…”

“…As a relatively stable gas, nitrogen generally does not undergo chemical reactions with other substances. It has strong compressibility and does not cause corrosion issues after injection. , It can quickly replenish reservoir pressure and replace the remaining oil at the top due to its high position resulting from gravity differentiation. , Additionally, it increases the elastic energy, delaying the time for water to reassemble, , achieving the effect of water control and stable production. However, gas channeling is easily prone to occurring in nitrogen flooding .…”