New well pattern optimization methodology in mature low-permeability anisotropic reservoirs

The diamond-shape inverted nine-spot well pattern is widely used in developing low-permeability reservoirs with fractures. However, production wells with equal fracture lengths will lead to nonuniform displacement, especially in anisotropic reservoir. Previous researches mainly focused on equal-length fractures, while studies on the unequal-length fractures which can dramatically improve the development efficiency were little. In this paper, a corresponding numerical model with unequal length of fracture designed in the edge and the corner wells was built in a low-permeability anisotropic reservoir. The main objective was to examine and evaluate the effects of anisotropic permeability and fracture parameter on the waterflooding in the diamond-shape inverted nine-spot well pattern. The results indicate that different fractures penetration ratio and anisotropic permeability both result in different development efficiency. Fracture of the edge well are more easily to be water breakthrough, while the increase of penetration ratio of injection well effectively enhance oil recovery. Moreover, the most optimal penetration ratios of production well fractures under different kx : ky are determined. With the increase of kx : ky, the optimized penetration ratio of corner wells fracture decrease, while that of the edge wells increase. Setting unequal length fractures in low-permeability anisotropic reservoirs can effectively improve the oil displacement efficiency in the waterflooding process.

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Study on Well Pattern Optimization of Tight Sandstone Gas Reservoir with the Strong Heterogeneity

10.2523/iptc-17190-ms ◽

2013 ◽

Author(s):

Ji Zhang ◽

Tao Lu ◽

Yuegang Li ◽

Shuming Yu ◽

Jingbu Li ◽

...

Keyword(s):

Tight Sandstone ◽

Gas Reservoir ◽

Well Pattern ◽

Well Pattern Optimization

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Reservoir characteristics and effective development technology in typical low-permeability to ultralow-permeability reservoirs of China National Petroleum Corporation

Energy Exploration & Exploitation ◽

10.1177/01445987211005212 ◽

2021 ◽

pp. 014459872110052

Author(s):

Xizhe Li ◽

Zhengming Yang ◽

Shujun Li ◽

Wei Huang ◽

Jianfei Zhan ◽

...

Keyword(s):

Horizontal Well ◽

Water Flooding ◽

Low Permeability ◽

Reservoir Characteristics ◽

Well Pattern ◽

China National Petroleum Corporation ◽

Volume Fracturing ◽

Effective Development ◽

Oil Gas ◽

Ultralow Permeability

Low-permeability to ultralow-permeability reservoirs of the China National Petroleum Corporation are crucial to increase the reserve volumes and the production of crude oil in the present and future times. This study aimed to address the two major technical bottlenecks faced by the low-permeability to ultralow-permeability reservoirs by a comprehensive use of technologies and methods such as rate-controlled mercury injection, nuclear magnetic resonance, conventional logging, physical simulation, numerical simulation, and field practices. The reservoir characteristics of low-permeability to ultralow-permeability reservoirs were first analyzed. The water flooding development adjustment mode in the middle and high water-cut stages for the low-permeability to ultralow-permeability reservoirs, where water is injected along the fracture zone and lateral displacement were established. The formation mechanism and distribution principles of dynamic fractures, residual oil description, and expanding sweep volume were studied. The development mode for Type II ultralow-permeability reservoirs with a combination of horizontal well and volume fracturing was determined; this led to a significant improvement in the initial stages of single-well production. The volume fracturing core theory and optimization design, horizontal well trajectory optimization adjustment, horizontal well injection-production well pattern optimization, and horizontal well staged fracturing suitable for reservoirs with different characteristics were developed. This understanding of the reservoir characteristics and the breakthrough of key technologies for effective development will substantially support the oil-gas valent weight of the Changqing Oilfield to exceed 50 million tons per year, the stable production of the Daqing Oilfield with 40 million tons per year (oil-gas valent weight), and the realization of 20 million tons per year (oil-gas valent weight) in the Xinjiang Oilfield.

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Gas drainage radius evaluation and well pattern optimization of multilayer gas reservoirs

IOP Conference Series Materials Science and Engineering ◽

10.1088/1757-899x/793/1/012047 ◽

2020 ◽

Vol 793 ◽

pp. 012047

Author(s):

Zhijun Liu ◽

Zhenglin Mao ◽

Haobo Zhang ◽

Yongbin Zhang ◽

Qian Liu ◽

...

Keyword(s):

Gas Reservoirs ◽

Gas Drainage ◽

Drainage Radius ◽

Well Pattern ◽

Well Pattern Optimization

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The Research of Flood Pattern Completeness in the Thin and Poor Oil Layers of South West II Area

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.594-597.2541 ◽

2012 ◽

Vol 594-597 ◽

pp. 2541-2544

Author(s):

Xiao Hui Wu ◽

Kao Ping Song ◽

Chi Dong ◽

Ji Cheng Zhang ◽

Jing Fu Deng

Keyword(s):

Oil Recovery ◽

Water Flooding ◽

South West ◽

Oil Distribution ◽

Well Pattern ◽

Remaining Oil ◽

Tertiary Oil Recovery ◽

Well Pattern Optimization ◽

Numerical Simulation Technique

As line well pattern is the main development technique in the thin and poor oil layers of Daqing Oilfield South West Ⅱ PⅠ group, the layers have been idle and the degree of reserve recovery is far less than the region level. In response to these problems, we analyzed the balanced flood performance of various layers and the remaining oil distribution through numerical simulation technique. It shows that, the main remaining oil type of intended layers is caused by voidage-injection imperfection. Considering the needs of the follow-up infill well pattern and tertiary oil recovery, we decided to keep the well network independent and integrated without disturbing the pattern configuration and main mining object of various sets of well pattern. Finally we confirmed to perforate-adding the first infill wells of intended layers to consummate the water flooding regime. Through analyzing the production target of different well pattern optimization programs relatively, it shows that the best program has regular well pattern and large drilled thickness.

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New Calculation Method of Sweep Efficiency after Pattern Infilling in Low Permeability Reservoir

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1010-1012.1713 ◽

2014 ◽

Vol 1010-1012 ◽

pp. 1713-1718

Author(s):

Fang Zhao ◽

Rui Shen ◽

Gang Xu

Keyword(s):

Calculation Method ◽

Statistical Data ◽

Effective Means ◽

Low Permeability ◽

Effect Evaluation ◽

Sweep Efficiency ◽

Well Spacing ◽

Well Pattern ◽

Development Effectiveness ◽

Result Show

Sweep efficiency is a very important parameters for development effect evaluation and dynamic analysis of oilfield. For low permeability oilfield, well pattern thickening is one of the most effective means of improving development effectiveness. In this paper, a corrected calculation method is given and well spacing density is introduced as a parameter for the formula correction. The curve of volumetric sweep efficiency and well spacing density was achieved through the formula and statistical data. After the infill adjustment, increasing multiple of sweep efficiency can be calculated. Using the actual data of Changqing oilfield to calculate, result show that the deviation is 1.1% .

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Analysis of hydraulic fracture behavior and well pattern optimization in anisotropic coal reservoirs

Energy Exploration & Exploitation ◽

10.1177/0144598720960833 ◽

2020 ◽

pp. 014459872096083

Author(s):

Yulong Liu ◽

Dazhen Tang ◽

Hao Xu ◽

Wei Hou ◽

Xia Yan

Keyword(s):

Hydraulic Fracture ◽

Coalbed Methane ◽

Fracture Network ◽

Simulation Software ◽

Natural Fracture ◽

Hydraulic Fractures ◽

Natural Fractures ◽

Well Pattern ◽

Well Pattern Optimization ◽

The Impact

Macrolithotypes control the pore-fracture distribution heterogeneity in coal, which impacts stimulation via hydrofracturing and coalbed methane (CBM) production in the reservoir. Here, the hydraulic fracture was evaluated using the microseismic signal behavior for each macrolithotype with microfracture imaging technology, and the impact of the macrolithotype on hydraulic fracture initiation and propagation was investigated systematically. The result showed that the propagation types of hydraulic fractures are controlled by the macrolithotype. Due to the well-developed natural fracture network, the fracture in the bright coal is more likely to form the “complex fracture network”, and the “simple” case often happens in the dull coal. The hydraulic fracture differences are likely to impact the permeability pathways and the well productivity appears to vary when developing different coal macrolithtypes. Thus, considering the difference of hydraulic fracture and permeability, the CBM productivity characteristics controlled by coal petrology were simulated by numerical simulation software, and the rationality of well pattern optimization factors for each coal macrolithotype was demonstrated. The results showed the square well pattern is more suitable for dull coal and semi-dull coal with undeveloped natural fractures, while diamond and rectangular well pattern is more suitable for semi-bright coal and bright coal with more developed natural fractures and more complex fracturing fracture network; the optimum wells spacing of bright coal and semi-bright coal is 300 m and 250 m, while that of semi-dull coal and dull coal is just 200 m.

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