Research of CO2 Huff and Puff Technology Applied to Horizontal Well Energy Replenishment in Tight Oil Reservoirs of A Area

The proven unused and controlled reserves of tight oil blocks are huge, however, under the elastic development of horizontal wells in tight oil reservoirs, there are many problems such as rapid production decline, low production, ineffective conventional water injection development, and large energy gaps in the formation. Effective technical means are urgently needed to supplement the energy of the formation. In order to explore new ways to effectively utilize tight oil blocks and improve the utilization of remaining oil in tight reservoirs, a carbon dioxide huff and puff pilot test was conducted in a horizontal well in A area in 2020. The daily oil production of a single well increased from 1.7t/d before huff and puff to 8.6t/d, and the test results were significant. The dynamic characteristics of carbon dioxide huff and puff applied to supplement energy in horizontal wells in tight reservoirs were determined, achieving a breakthrough in the production improvement effect of high viscosity crude oil and strong water sensitive tight reservoirs. Based on the results of this experiment, combined with on-site test data tracking and analysis, numerical simulation, fine modeling and other technologies were further utilized to optimize multiple injection and production technical parameters such as gas injection rate, injection rate, and soaking time. Carbon dioxide huff and puff was performed on selected horizontal wells in the A area in 2022. The daily oil production of a single well increased from 0.4t/d before huff and puff to 4.4t/d, and the water content decreased by 32.6 percentage points, the goal of effectively reducing water content while increasing production has been achieved, and the application effect of carbon dioxide huff and puff technology in the development of horizontal wells in tight oil reservoirs in peripheral oilfields has been improved. This provides ideas and technical support for the energy replenishment of horizontal wells in tight oil reservoirs in the future.