Modeling and Simulation of Hydraulic Fractures Coupling with Natural Fractures in Tight Sandstone Reservoir of Triassic Formation

2018 ◽  
Author(s):  
Gang Hui ◽  
Nancy Chen ◽  
Youjing Wang
Keyword(s):  
Modeling And Simulation ◽  
Hydraulic Fractures ◽  
Natural Fractures ◽  
Tight Sandstone ◽  
Sandstone Reservoir

scholarly journals Fracability Evaluation Method and Influencing Factors of the Tight Sandstone Reservoir

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Jiageng Liu ◽  
Lisha Qu ◽  
Ziyi Song ◽  
Jing Li ◽  
Chen Liu ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Horizontal Stress ◽  
High Fracture Toughness ◽  
Hydraulic Fractures ◽  
Anisotropy Coefficient ◽  
Natural Fractures ◽  
Fracture Networks ◽  
Tight Sandstone ◽  
Stress Anisotropy ◽  
Sandstone Reservoir

Fracability evaluation is the basis of reservoir fracturing and fracturing zone optimization. The tight sandstone reservoir is characterized by low porosity and low permeability, which requires hydraulic fracturing to improve industrial productivity. In this study, a systematic model was proposed for the fracability evaluation of tight sandstone reservoirs. The rock mechanics tests and sonic tests demonstrated that tight sandstone reservoir is characterized by high brittleness, high fracture toughness, and weak development of natural fractures. Numerical simulation was used to analyze the change of reservoir parameters during hydraulic fracturing and the influence of in situ stress on fracture propagation. The results showed that when the horizontal stress anisotropy coefficient is small, natural fractures may lead hydraulic fractures to change direction, and complex fracture networks are easily formed in the reservoir. The horizontal stress anisotropy coefficient ranges from 0.23 to 0.52, and it is easy to produce fracture networks in the reservoir. A new fracability evaluation model was established based on the analytic hierarchy process (AHP). The fracability of tight sandstone reservoir is characterized by the fracability index (FI) and is divided into three levels. Based on the model, this study carried out fracability evaluation and fracturing zone optimization in the study area, and the microseismic monitoring results verified the accuracy of the model.

scholarly journals The Effect of Hydraulic-Natural Fracture Networks on the Waterflooding Development in a Multilayer Tight Reservoir: Case Study

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Gang Hui ◽  
Shengnan Chen ◽  
Youjing Wang ◽  
Fei Gu
Keyword(s):  
Spatial Distribution ◽  
Natural Fracture ◽  
Hydraulic Fractures ◽  
Sand Layer ◽  
Natural Fractures ◽  
Fracture Networks ◽  
Tight Sandstone ◽  
Water Breakthrough ◽  
Sand Bodies

An integrated hydraulic fracturing followed by waterflooding was conducted in a heterogeneous sandstone formation in the Northern Shanxi Slop of Ordos Basin in Western China. Water breakthrough quickly occurred, and the underlying mechanism of water breakthrough has not been well understood. Such mechanism needs to be investigated comprehensively from the spatial connectivity of multilayer sand bodies and characterization of hydraulic-natural fracture networks. Here, an integrated approach is proposed to tap the remaining oil in the individual sand layer during the late-stage development of tight sandstone reservoirs. A case study is utilized to demonstrate the applicability of the integrated method. It is found that the six sand layers could be further divided within the target oil layers. These sand layers have a variety of physical and mechanical properties, leading to the asymmetric spatial distribution of hydraulic fractures after performing the integrated fracturing of whole oil layers. The spatial difference of sand bodies conforms to the features of the multiperiod superimposed channel in the sedimentary environment of fan delta front. The natural fractures were generated from the tectonic movement in the Mesozoic period with a dominant orientation of approximately NE 67°. The asymmetric hydraulic fractures propagated and connected with the preexisting natural fractures, forming the intricate natural-hydraulic fracture networks. The water breakthrough pattern in each sand layer is primarily ascribed to the spatial distribution of the hydraulic-natural fracture networks and sedimentary microfacies. The refracturing operations based on the remaining oil distribution in sand layers are proven to be effective in further developing the formation. The average oil production of related wells increased from 0.61 t/d to 2.18 t/d. This practical development strategy provides insights for further development of likewise heterogeneous tight sandstone reservoirs.

Fracturing Well Production Dynamic Simulation in Fractured Tight Sandstone Gas Reservoir

2013 ◽  
Vol 457-458 ◽  
pp. 410-415
Author(s):  
Chao Yang Xie ◽  
Yong Quan Hu ◽  
Xing Chen ◽  
Ying Chao Ma ◽  
Jin Zhou Zhao ◽  
...  
Keyword(s):  
Flow Coefficient ◽  
Production Performance ◽  
Natural Fracture ◽  
Inverse Transformation ◽  
Hydraulic Fractures ◽  
Fractured Reservoir ◽  
Tight Sandstone ◽  
Gas Reservoir ◽  
Sandstone Reservoir ◽  
Effective Development

The tight sandstone formation usually has natural fracture, which is the foundation of effective development using hydraulic fracturing. The conventional reservoir productivity simulation method don't adapt to it. In this paper, Warren & Root model was used for describing infinity tight fractured reservoir model with vertical hydraulic fractures. Then, assuming the fracture length and the width does not vary with time and formation pressure, fracture seepage equation was obtained in base of the one-dimensional flow Darcy percolation equation and continuity equation. By Stehfese, a method of numerical inverse transformation, production performance simulation model was established for natural fractured tight sandstone reservoir. Taking for actual example from Daqing oilfield, affection of characteristics of natural fractures and artificial fracture parameters on productivity of natural fractured tight sandstone reservoir were analyzed. Elastic storability ratio has a greater influence than interporosity flow coefficient. It was the core technique for the gas reservoir to effective development by large amount of fluid and low sand ratio.

scholarly journals A reservoir quality evaluation approach for tight sandstone reservoirs based on the gray correlation algorithm: A case study of the Chang 6 layer in the W area of the as oilfield, Ordos Basin

2021 ◽  
pp. 014459872199851
Author(s):  
Yuyang Liu ◽  
Xiaowei Zhang ◽  
Junfeng Shi ◽  
Wei Guo ◽  
Lixia Kang ◽  
...  
Keyword(s):  
Quality Evaluation ◽  
Comprehensive Evaluation ◽  
Ordos Basin ◽  
Reservoir Quality ◽  
Pore Throat ◽  
Tight Sandstone ◽  
Evaluation Approach ◽  
Correlation Algorithm ◽  
Gray Correlation ◽  
Sandstone Reservoir

As an important type of unconventional hydrocarbon, tight sandstone oil has great present and future resource potential. Reservoir quality evaluation is the basis of tight sandstone oil development. A comprehensive evaluation approach based on the gray correlation algorithm is established to effectively assess tight sandstone reservoir quality. Seven tight sandstone samples from the Chang 6 reservoir in the W area of the AS oilfield in the Ordos Basin are employed. First, the petrological and physical characteristics of the study area reservoir are briefly discussed through thin section observations, electron microscopy analysis, core physical property tests, and whole-rock and clay mineral content experiments. Second, the pore type, throat type and pore and throat combination characteristics are described from casting thin sections and scanning electron microscopy. Third, high-pressure mercury injection and nitrogen adsorption experiments are optimized to evaluate the characteristic parameters of pore throat distribution, micro- and nanopore throat frequency, permeability contribution and volume continuous distribution characteristics to quantitatively characterize the reservoir micro- and nanopores and throats. Then, the effective pore throat frequency specific gravity parameter of movable oil and the irreducible oil pore throat volume specific gravity parameter are introduced and combined with the reservoir physical properties, multipoint Brunauer-Emmett-Teller (BET) specific surface area, displacement pressure, maximum mercury saturation and mercury withdrawal efficiency parameters as the basic parameters for evaluation of tight sandstone reservoir quality. Finally, the weight coefficient of each parameter is calculated by the gray correlation method, and a reservoir comprehensive evaluation indicator (RCEI) is designed. The results show that the study area is dominated by types II and III tight sandstone reservoirs. In addition, the research method in this paper can be further extended to the evaluation of shale gas and other unconventional reservoirs after appropriate modification.

Sign in / Sign up

Export Citation Format

Share Document