National Engineering Laboratory of Low Permeability Oilfield Exploration and Development

Fengcheng, China

National Engineering Laboratory of Low Permeability Oilfield Exploration and Development

Fengcheng, China

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Lei Q.-H.,Petrochina | Lei Q.-H.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | Cheng L.-B.,Petrochina | Cheng L.-B.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | And 8 more authors.
Natural Gas Geoscience | Year: 2017

Ordos Basin is abundant in tight oil resource in Chang 7 Formation. Physical properties are poor in the reservoir with air permeability of less than 0.3×10-3μm2. This reservoir can be evaluated by movable fluid saturation which is considered as one of the most significant parameters. Combined with centrifuge tests and NMR T2 spectrum analysis, the movable fluids distribution of Chang 7 tight reservoir in Ordos Basin was figured out. The results show that: firstly, the average mono-phase saturation of movable water in Chang 7 tight oil reservoirs is 39.40%. While the movable water saturation in the pore throat which are divided to micron (greater than 1μm), sub-micron(0.1 to 1μm) or nano(less than 0.1μm), are respectively 2.2%, 25.67% and 11.52%; the average movable oil saturation is 26.07% in bound water saturation, and the movable oil saturation in micron, submicron or nano-pore throat is 0.79%, 9.48% and 15.81%, respectively; the movable fluids exist mainly in the submicron and nano-pore throat. Second, the movable water or oil saturation will increase with the increase of core permeability, but the trends of movable fluids saturation differ from the size of pore throat. When throat radius is 0.1 to 0.5 micrometer, the movable fluids saturation increases the biggest growth with core permeability, next is the radius of 0.5 to 1.0 micrometer, and the radius greater than 1.0 micrometer, the growth is the least. However, when throat radius is less than 0.1 micrometer, the relative contents of movable fluids saturation decrease obviously. © 2017, Science Press. All right reserved.


Li Z.-X.,Petrochina | Li J.,Petrochina | Qu X.-F.,Petrochina | Qu X.-F.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | And 6 more authors.
Natural Gas Geoscience | Year: 2015

Chang 7 tight oil is characterized by poor physical properties, low formation pressure coefficient, well-developed natural fractures and high friability. In order to realize the goal of effective development with low-pressure tight oil, research has been carried out on three aspects to improve the early stages of single well production, stabilize for long time and reduce the cost through a series of field tests. After the four-stage technical innovation, great breakthrough has been achieved on tight oil development test, key technology for low-pressure tight oil has been established such as reservoir reconstruction technology of horizontal well volume fracturing, horizontal well development technique policy optimization, technology of reducing cost and increasing economic benefits, and four aspects of main knowledge have been gained as following: (1) long horizontal length plus volume fracturing are the core of promoting well production; (2) currently it is preferable to utilize approximate natural energy at the initial stage and energy supplement at later stage for horizontal wells with long horizontal length, volume fracturing; (3) controlled oil production is beneficial to promote tight oil development effects; (4) cost-reducing and efficiency-enhancing are important ways of exploiting tight oil economically and effectively. © 2015, Science Press. All right reserved.


Zhao J.,Petrochina | Zhao J.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | Fan J.,Petrochina | Fan J.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | And 6 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2015

There are two kinds of displacement mechanisms and three different seepage stages during horizontal well development process with water injection energy. A reasonable injection-production working system of the basic principles and parameters are determined according to the evaluation results of horizontal well development test on the basis of understanding fundamental rules. (1) Advanced water injection energy supplement mode is proposed with the combination of injection wells and large volume water fracturing of horizontal wells. (2) Theoretical calculation chart of directional well advanced water injection and water injection intensity is established for various reservoirs. (3) The timing of advanced water injection should follow the completion of the horizontal wells. (4) Reasonable initial production of horizontal well is determined by the relationship of remaining fluid volume with row spacing, advanced injection water volume and flood front advancing velocity. (5) Reasonable production flowing pressure is slightly greater than saturation pressure before water injection does not work, when it works, the reasonable production flow pressure maintains no less than two-thirds of saturation pressure, and adjust it timely combining with dynamic production. Based on the research results, the HQ oilfield put 80 horizontal wells into production during 2013, the proportion of water-breakthrough wells reduces from 8.8% to 3.0%, the annual decrease of the average production of single horizontal well is controlled within 15%. ©, 2015, Science Press. All right reserved.


Fan J.,Petrochina | Fan J.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | Qu X.,Petrochina | Qu X.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | And 8 more authors.
Shiyou Kantan Yu Kaifa/Petroleum Exploration and Development | Year: 2016

Based on core, imaging logging, and thin section data, the distribution features of natural fractures in the tight oil reservoirs of the Ordos Basin are examined. The tight reservoirs in the Ordos Basin are rich in natural fractures, the fractures are mainly high-angle structural shear fractures in continuous step arrangement. Affected by rock mechanical anisotropy and present stress field, the NE trending fractures are the dominating seepage flow direction. These fractures feature high angle, small cutting depth, small aperture and short extension, controlled by rock lithology and single layer thickness in development degree, natural fractures are most developed in fine siltstone, most undeveloped in mudstone. The thinner the single layer, the more developed the natural fractures will be. Based on distribution features of natural fractures and quantitative evaluation of natural fracture characteristic parameters, by using reservoir matrix and natural fracture geologic modeling, a comprehensive reservoir geologic model considering natural fractures was built, by using reservoir numerical simulation modeling inversion, the plane distribution of effective natural fractures was found out, and the contribution of natural fractures to single well production was quantitatively evaluated at around 30.0%-50.0%. The research results are of great significance for well-pattern deployment and optimization of development technical policies of similar reservoirs. © 2016, The Editorial Board of Petroleum Exploration and Development. All right reserved.


Zhao J.,Petrochina | Zhao J.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | Fan J.,Petrochina | Fan J.,National Engineering Laboratory of Low Permeability Oilfield Exploration and Development | And 6 more authors.
Petroleum Exploration and Development | Year: 2015

There are two kinds of displacement mechanisms and three different seepage stages during horizontal well development process with water injection energy. A reasonable injection-production working system of the basic principles and parameters are determined according to the evaluation results of horizontal well development test on the basis of understanding fundamental rules. (1) Advanced water injection energy supplement mode is proposed with the combination of injection wells and large volume water fracturing of horizontal wells. (2) Theoretical calculation chart of directional well advanced water injection and water injection intensity is established for various reservoirs. (3) The timing of advanced water injection should follow the completion of the horizontal wells. (4) Reasonable initial production of horizontal well is determined by the relationship of remaining fluid volume with row spacing, advanced injection water volume and flood front advancing velocity. (5) Reasonable production flowing pressure is slightly greater than saturation pressure before water injection does not work, when it works, the reasonable production flow pressure maintains no less than two-thirds of saturation pressure, and adjust it timely combining with dynamic production. Based on the research results, the HQ oilfield put 80 horizontal wells into production during 2013, the proportion of water-breakthrough wells reduces from 8.8% to 3.0%, the annual decrease of the average production of single horizontal well is controlled within 15%. © 2015 Research Institute of Petroleum Exploration & Development, PetroChina.

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