Best Practices in Development and Production Optimization of Offshore Low Permeability Reservoir

2021 ◽  
Author(s):  
Lijian Zhang ◽  
Panpan Tian ◽  
Chuanheng Xing ◽  
Ruiting Bai ◽  
Yanjun Yin ◽  
...  

Abstract The development effect of low permeability reservoirs of offshore Shahejie Formation in China is poor with fast formation pressure drop, rapid production decline and numerous abnormal wells due to the influence of low permeability, strong heterogeneity, ultra-high reservoir temperature and pressure and high wax and asphaltene content. To overcome these difficulties, this paper takes geological conditions, reservoir potential, stimulation technology and actual wells situation into consideration on the basis of the reservoir performance research, and gives full play to the integration of reservoir and mechanical recovery. A set of production enhancement and efficiency improvement technologies has been formed, including moderate periodic water injection based on pressure fluctuation theory, liquid extraction optimization for low permeability fields, modified compound plugging removal technology, small flowrate and broad width electric pump selection technology, and pump stuck early warning technique to achieve the efficient development of offshore low-permeability oilfields. Moderate periodic water injection not only makes full use of the imbibition effect to achieve the equilibrium displacement, but also avoids the water channeling in fracture area; eight main controlling factors are used to classify and evaluate the liquid extraction potential and select the well group at level-1 for the workover with the effect of daily oil increase of 42 m3; modified compound plugging removal technique completely removes the pollution and plugging of the formation and the wellbore to release the potential of the oil wells to the greatest extent and cumulative oil increase of 6 well times is expected to be 12.44×104 m3; small flowrate and broad width electric pump selection technology applied for more than 30 well times improves the adaptability of the pumps substantially and extends the pump inspection cycle to 857 days; real-time pump stuck warning technique through the dual pattern of analyzing both conventional and high-frequency data guarantees the efficient operation of oil wells. The technologies in this paper have been applied in the target low-permeability field with daily oil production of 429 m3, oil recovery rate of 1.1%, natural decline rate drop year by year and the expected recovery factor of 20.9% under current well pattern. The key technologies in this paper have improved the target reservoir development effect significantly and provided important reference significance for other offshore low-permeability reservoirs development.

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 832-838 ◽  
Author(s):  
Lijun Lin ◽  
Wei Lin

AbstractThe rhombus inverted nine-spot well pattern is often adopted in low permeability oilfield development, which has the advantage of high oil production rate and flexible adjustment. Due to the strong heterogeneity of the low permeability reservoirs, the oil wells along the fracture direction are heavily water-flooded and the water cut rises quickly, and the oil wells on both sides of fractures have no response to water injection. Hence, deep profile control is an effective way to solve this kind of plane contradiction, and is widely applied in the low permeability oilfield development. However, because of the asymmetry of the rhombus inverted nine-spot well pattern and the heterogeneity of the low permeability reservoirs, there are differences in the response characteristics of oil wells at different locations after deep profile control. In this paper, combined with physical experiments and numerical simulations, we analyzed oil increment, the distribution of streamlines and slugs of wells at different locations before and after deep profile control, and evaluated the response characteristics of oil wells of rhombus inverted nine-spot well pattern after deep profile control in low permeability fractured reservoirs. It is concluded that the effect of increasing oil production of the side wells is better than that of the angle wells after deep profile control, and the response sequence is side well, angle well in short axis, and angle well in long axis, which is also verified by the practical results of deep profile control in Daqing Oilfield.


2014 ◽  
Vol 1073-1076 ◽  
pp. 2310-2315 ◽  
Author(s):  
Ming Xian Wang ◽  
Wan Jing Luo ◽  
Jie Ding

Due to the common problems of waterflood in low-permeability reservoirs, the reasearch of finely layered water injection is carried out. This paper established the finely layered water injection standard in low-permeability reservoirs and analysed the sensitivity of engineering parameters as well as evaluated the effect of the finely layered water injection standard in Block A with the semi-quantitative to quantitative method. The results show that: according to the finely layered water injection standard, it can be divided into three types: layered water injection between the layers, layered water injection in inner layer, layered water injection between fracture segment and no-fracture segment. Under the guidance of the standard, it sloved the problem of uneven absorption profile in Block A in some degree and could improve the oil recovery by 3.5%. The sensitivity analysis shows that good performance of finely layered water injection in Block A requires the reservoir permeability ratio should be less than 10, the perforation thickness should not exceed 10 m, the amount of layered injection layers should be less than 3, the surface injection pressure should be below 14 MPa and the injection rate shuold be controlled at about 35 m3/d.


2013 ◽  
Vol 295-298 ◽  
pp. 3162-3165
Author(s):  
Lu Lu Zhou ◽  
Zi Nan Li ◽  
Jun Gang Liu ◽  
Yan Yun Zhang ◽  
Guang Qiang Shu

Taking the example of the fourth member of the Lower Cretaceous Quantou formation reservoirs in fault block Sheng554 of Sanzhao sag, this article discusses the methodology of flow units in extra-low permeability reservoirs. The research on flow units in such reservoirs can be divided into two ranks, one is to determine the distribution of seepage barriers and inner connected sands, the other is to analyze the differentia of fluid flow in the inner connected sands so as to subdivide the flow units. The result shows that the pelitic barriers are rather developed in fault block Sheng554. Through the analysis of differentia of fluid flow, according to the value of flow zone index (FZI), the inner connected sands can be classified into three types of flow units, among which type A with FZI value greater than 1.0 has better permeable property and higher intensity of water injection, and the ability of permeability and water injection of type B with FZI value between 0.5 and 1.0 takes the second place, and type C is the worst flow unit with the worst permeable property and intensity of water injection with FZI value less than 0.5. Among the three types of flow units, type A poorly develops, while type B and type C develops well. The research on flow units can provide reliable geologic bases for forecasting the distribution of remaining oil in extra-low permeability reservoirs and for developing remaining oil in the study area.


2019 ◽  
Vol 11 (5) ◽  
pp. 168781401984676 ◽  
Author(s):  
Chengyong Li ◽  
Jing Yang ◽  
Jianwen Ye ◽  
Jun Zhou ◽  
Ran Zhang ◽  
...  

Author(s):  
Boying Li ◽  
Yuhui Zhou ◽  
Su Li ◽  
Yiping Ye ◽  
Hongfa Liu

AbstractFault-karst reservoirs are featured by complex geological characteristics, and accurate and fast simulation of such kind of reservoirs using traditional simulator and simulation methods is pretty hard. Herein, we tried to discrete the complex fault-karst structures into one-dimensional connected units connecting the well, fracture and cave based on reservoir static physical parameters and injection-production dynamics. Two characteristic parameters, conductivity and connected volume, are proposed to characterize the inter-well connectivity and material basis. Meanwhile, the high-speed non-Darcy seepage term is introduced into the material balance equations for well-fracture-cave connected units to describe the actual seepage characteristics within the fault-karst reservoirs, and to better simulate the oil/water production dynamics. Based on this method, a fracture reservoir model of 1 injection-3 production was established. The change of oil–water action law in different injection and extraction systems under two production regimes of fixed production rate and fixed pressure is analyzed. A case study was conducted on S fault zone, where the flow of oil and gas did not follow the Darcy seepage rule and with a β value of 103–104, the single well flow pressure and oil production were perfectly matched with the real data. In addition, connected units with more prominent high-speed non-Darcy features were found to have better connectivity, which might shed light on the more accurate prediction of inter-well connectivity. Moreover, an improved injection-production well pattern and was proposed based on connectivity prediction model and reservoir engineering method to solve the problems of insufficient natural energy supply and overhigh oil production rate in Block S. Furthermore, the injection/production rate as well as the timing and cycle of water injection was predicted and optimized so as to better guide to site operations.


2013 ◽  
Vol 274 ◽  
pp. 153-156
Author(s):  
Rong Hua Li ◽  
Jun Ting Zhang ◽  
Cheng Lin Zhang ◽  
Huan Huan Zhang ◽  
Peng Qu

Layer system subdivision and adjustment is applied in oilfield development to ease the contradiction in inner-layer and interlayer and implement separated layer water flooding well, which is a major adjustment measure to improve developing effects. YSL is a typical low-permeability oil field, whose petrophysics is poor, and which exist many problems, such as apparent contradictions between layers, and poor development effects through separated zone water injection and so on. In this article, the thickness of barriers, injection profile, permeability contrast and remaining oil distribution are analyzed comprehensively. So a reasonable method is also proposed. Much weakness that factors are not comprehensive in adjustment method and that the problems in the development process are not accurately reflected is overcome, which exists in the past methods. The adjustment means can utilize poor thin layers better, reduce invalid water injection and ease the contradictions between layer, and oilfield development effects are improved eventually. It is a reference and guidance for other blocks or oilfield which exist the same problems.


2016 ◽  
Author(s):  
Shuai Wang ◽  
Ji Tian ◽  
Xianhong Tan ◽  
Ling Wang ◽  
Shaohui Zhang

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