A New Re-Fracturing Candidate Selection Method for Multi-Fractured Horizontal Well in Tight Oil Reservoirs

2021 ◽  
Author(s):  
Liang Tao ◽  
Xiaozhuo Zhang ◽  
Shubo Yang ◽  
Sheng Xian ◽  
Yuhang Zhao ◽  
...  

Abstract The selection of refracturing candidate is the primary challenge of refracturing technology. There are many factors affecting the selection of refracturing candidate for multi-fractured horizontal wells (MFHWs) and the relationship between each factor is very complicated, which makes it very difficult to select the optimal wells. A new method combining initial completion efficiency and production performance was proposed in this study to solve this problem. First, the fracture parameters were obtained by fitting method to evaluate the initial completion efficiency. Then, the geological model was established by the method of reservoir numerical simulation to evaluate the dynamic effect of production. Finally, the potential of refracturing was evaluated. The new method has been successfully applied to 30 wells of the tight oil reservoirs in Songliao Basin China. The average daily oil production was 18.5 tons/day after refracturing treatment. This research could provide significant guidance for the development of tight oil reservoirs.

2021 ◽  
Author(s):  
Liang Tao ◽  
Jianchun Guo ◽  
Zhijun Li ◽  
Xuanyi Wang ◽  
Shubo Yang ◽  
...  

Abstract Single well productivity is an important index to evaluate the effect of volume fracturing. However, there are many factors affecting the productivity of Multi-fractured horizontal wells (MFHWs) in unconventional reservoirs and the relationship is complex, which makes productivity prediction very difficult. In this paper, taking the tight oil reservoir in Songliao Basin as the research object, a new mixed model of initial cumulative oil production of MFHWs was established, which can consider the geological factors and volume fracturing factors at the same time. Firstly, based on the big data, the multi-level evaluation system was established by using the analytic hierarchy process (AHP). Then, the weight factor was calculated to uncover key factors that dominate productivity of MFHWs. Finally, the fuzzy logic method was used to calculate the Euclidean distance and quantitatively predict the production of any horizontal wells. The simulation results shown that: the order of the main factors affecting production in the study area was horizontal section sandstone length, number of stages, formation pressure, proppant amount, net pay thickness, permeability, porosity, oil saturation, fracturing fluid volume. The hybrid model has been applied to the productivity prediction of 185 MFHWs in tight oil reservoirs in China, the prediction error was less than 5%. The new model can be used to predict production for MFHWs quickly and economically.


Geofluids ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Mingqiang Hao ◽  
Songlin Liao ◽  
Guangming Yu ◽  
Xinhui Lei ◽  
Yong Tang

In this paper, the sensitivity factors of CO2 huff-n-puff for multifractured horizontal wells (MFHWs) in tight oil reservoirs were investigated through an experimental test and numerical simulation. The pressure-volume-temperature (PVT) experiment and the slim tube experiment are used to understand the interaction mechanism between CO2 and crude oil, and the minimum miscibility pressure (MMP) of the CO2-crude oil system is 17 MPa. The single-well model was firstly established to analyze the sensitivity factors on production performance of MFHWs by using CO2 huff-n-puff. The controlling factors of CO2 huff-n-puff for MFHWs in tight oil reservoirs were divided into three categories (i.e., reservoir parameters, well parameters, and injection-production parameters), and the impact of individual parameter on well performance was discussed in detail. The range of reservoir parameters suitable for CO2 huff-n-puff of MFHWs is obtained. The reservoir permeability is from 0.1 mD to 1 mD, the reservoir thickness changes from 10 m to 30 m, and the reservoir porosity is from 7% to 12%. Based on the reservoir parameters of the target reservoir, the reasonable well and fracture parameters are obtained. The sensitivity intensity was followed by the horizontal well length, fracture conductivity, fracture spacing, and fracture half-length. CO2 injection-production parameters are further optimized, and the sensitivity intensity was followed by the single-cycle cumulative CO2 injection rate, the soaking time, the injection rates, and the production rates. It provides a reference for parameter optimization of CO2 huff-n-puff for MFHWs in tight oil reservoirs.


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