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With the depletion of conventional resources, it is necessary to enhance the recovery of remaining oil. The tertiary oil recovery chemical flooding is the most promising for enhanced oil recovery (EOR). The use of alkali in chemical flooding produces fouling with the formation, which brings new challenges to chemical flooding EOR. So, alkali-free surfactant-polymer (SP) flooding is used as a new solution for EOR. The polymer makes the displacing fluid have a high viscosity and increases the swept volume. The surfactant can decrease the interfacial tension and emulsify the crude oil while the displacing fluid reaches the corresponding area. The synergistic effect of the two is more conducive to the recovery of the remaining oil. As a result, SP flooding is a more practical approach to enhance oilfield EOR. The research status of several surfactant and polymer types for EOR is reported in this work. According to the study, complex and anionic surfactants are better for EOR. For difficult formations, SP flooding is more suited because of the presence of polymers. Additionally, study analysis demonstrates that SP flooding and alternative polymer injection, when employed at the same cost, can enhance EOR and assist in resolving issues brought on by low oil prices.

To clarify the dynamic evolution characteristics of reservoir flow units during water injection development, the upper member of the Neogene Guantao formation in Block M of Gudao Oilfield is taken as a case study. Based on logging data, water injection profile test data, subwell data, and production performance data, among others, the flow zone index (FZI static) was proposed as the static evaluation parameter of the flow unit. The relationship between cumulative water injection (WT) and FZI change ( △ FZI ) was fitted. Hence, the △ FZI caused by water injection is combined with the static parameter of flow unit evaluation (FZI static) as the dynamic parameter of flow unit evaluation (FZI dynamic). The comprehensively evaluated reality of flow units in different periods is characterized by formula FZI   static + △ FZI = FZI   dynamic . The study shows that as the division standard of the flow unit, the FZI has a good correlation with the test results of the water absorption profile, such as water absorption intensity and relative water injection volume. Using the FZI as the static parameter of flow unit evaluation, four types of flow units were divided as follows: type I flow unit, FZI ≥ 4.1 ; type II flow unit, 4.1 > FZI ≥ 2.4 ; type III flow unit, 2.4 > FZI ≥ 1.7 ; type IV flow unit, 1.7 > FZI . The reservoir porosity and permeability characteristics of different flow units are highly correlated. Moreover, the relative permeability curve confirms that different flow units have different seepage capacities. Though, comparing characteristic reservoir parameters in different periods, the reservoir’s physical parameters became more conducive to fluid flow with the water injection development. The increase in the same water injection rate for type I and II flow units was greater than that for type III and IV flow units. Furthermore, when type I flow units were continuously distributed in a large area, high water consumption bands were formed, absorbing most of the water injection in the water injection wells. Hence, the waterflood efficiency was low. The change in different flow units was mainly controlled by the injection production well pattern and WT. Combined with the relative change characteristics of interlayer flow units, the changes can be divided into increasing type change and decreasing type changes. Finally, according to the distribution characteristics of different flow units, oil saturation, and water flooding results, strategies for tapping the potential of the remaining oil from three aspects (plane, interlayer, and inner layer) were formulated.

As Operators face challenges due to increased water production worldwide the application of Passive and Autonomous Inflow Control Devices has proven effective at both delaying water production onset (passive functionality) and reducing water production at the surface (autonomous functionality). Passive technology has been deployed very effectively in hundreds of wells while autonomous devices are showing great promise to reduce costs, environmental risk, and potentially a significant reduction in topside infrastructure. Passive devices only delay the onset of unwanted fluid breakthrough. Once breakthrough occurs, these tools do not restrict production. This led to the development of AICD technology which provides passive functionality initially but restricts water production at breakthrough. This functionality is greatly enhanced when compartments are created downhole to enable a "network" of devices to function independently at breakthrough, allowing other compartments to produce oil relatively unrestricted. The design proposed in this paper uses no moving parts, significantly restricts water production in a wide range of crude viscosities, is easily configured for a variety of downhole conditions, and delivers passive ICD performance with AICD benefits using a simple, reliable, and unique design. The tool functions to restrict water production progressively as either oil viscosity or water cut increase without ever completely or nearly completely closing to production, which makes it an excellent solution for marginal production wells, younger reservoirs, and wells with lower overall production rates compared to other technologies. The paper will discuss the theory of the device's functionality to differentiate between fluids present. Laboratory test results will be shown to demonstrate flow performance as well as API 19ICD[1] testing for erosion, plugging resistance, and mud flow initiation testing. The completion modeling process will be discussed in detail for an upcoming completion in Sinopec's Shengli Field.

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