Enhancing gas production from Class II hydrate deposits through depressurization combined with low-frequency electric heating under dual horizontal wells

Energy ◽  
2021 ◽  
pp. 121137
Author(s):  
Ermeng Zhao ◽  
Jian Hou ◽  
Yunkai Ji ◽  
Yongge Liu ◽  
Yajie Bai
Keyword(s):  
Low Frequency ◽  
Horizontal Wells ◽  
Electric Heating ◽  
Class Ii ◽  
Gas Production

The Key Factors of Low-Frequency Electric Heating Assisted Depressurization Method in the Exploiting of Methane Hydrate Sediments

2021 ◽  
Author(s):  
Ermeng Zhao ◽  
Jian Hou ◽  
Yunkai Ji ◽  
Lu Liu ◽  
Yongge Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Low Frequency ◽  
Electric Heating ◽  
Gas Production ◽  
Hydrate Decomposition ◽  
Hydrate Saturation ◽  
Production Behavior

Abstract Natural gas hydrate is widely distributed in the permafrost and marine deposits, and is regarded as an energy resource with great potential. The low-frequency electric heating assisted depressurization (LF-EHAD) has been proven to be an efficient method for exploiting hydrate sediments, which involves complex multi-physics processes, i.e. current conduction, multiphase flow, chemical reaction and heat transfer. The physical properties vary greatly in different hydrate sediments, which may profoundly affect the hydrate decomposition in the LF-EHAD process. In order to evaluate the influence of hydrate-bearing sediment properties on the gas production behavior and energy utilization efficiency of the LF-EHAD method, a geological model was first established based on the data of hydrate sediments in the Shenhu Area. Then, the influence of permeability, porosity, thermal conductivity, specific heat capacity, hydrate saturation and hydrate-bearing layer (HBL) thickness on gas production behavior is comprehensively analyzed by numerical simulation method. Finally, the energy efficiency ratio under different sediment properties is compared. Results indicate that higher gas production is obtained in the high-permeability hydrate sediments during depressurization. However, after the electric heating is implemented, the gas production first increases and then tends to be insensitive as the permeability decreases. With the increasing of porosity, the gas production during depressurization decreases due to the low effective permeability; while in the electric heating stage, this effect is reversed. High thermal conductivity is beneficial to enhance the heat conduction, thus promoting the hydrate decomposition. During depressurization, the gas production is enhanced with the increase of specific heat capacity. However, more heat is consumed to increase the reservoir temperature during electric heating, thereby reducing the gas production. High hydrate saturation is not conducive to depressurization because of the low effective permeability. After electric heating, the gas production increases significantly. High HBL thickness results in a higher gas production during depressurization, while in the electric heating stage, the gas production first increases and then remains unchanged with the increase of thickness, due to the limited heat supply. The comparison results of energy efficiency suggest that electric heating is more advantageous for hydrate sediments with low permeability, high porosity, high thermal conductivity, low specific heat capacity, high hydrate saturation and high HBL thickness. The findings in this work can provide a useful reference for evaluating the application of the LF-EHAD method in gas hydrate sediments.

Mutation at autosomal loci of Chinese hamster ovary cells: involvement of a high-frequency event silencing two linked alleles

1983 ◽  
Vol 3 (7) ◽  
pp. 1172-1181
Author(s):  
W E Bradley
Keyword(s):  
Cell Lines ◽  
Chinese Hamster Ovary ◽  
High Frequency ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Low Frequency ◽  
Class Ii ◽  
Class I ◽  
Wild Type ◽  
Ovary Cells

Two classes of cell lines heterozygous at the galactokinase (glk) locus have been isolated from Chinese hamster ovary cells. Class I, selected by plating nonmutagenized wild-type cells at low density in medium containing 2-deoxygalactose at a partially selective concentration, underwent subsequent mutation to the glk-/- genotype at a low frequency (approximately 10(-6) per cell), which was increased by mutagenesis. Class II heterozygotes, isolated by sib selection from mutagenized wild-type cells, had a higher spontaneous frequency of mutation to the homozygous state (approximately 10(-4) per cell), which was not affected by mutagenesis. About half of the glk-/- mutants derived from a class II heterozygote, but not the heterozygote itself, were functionally hemizygous at the syntenic thymidine kinase (tk) locus. Similarly, a tk+/- heterozygote with characteristics analogous to the class II glk+/- cell lines underwent high-frequency mutation to tk-/-, and most of these mutants, but not the tk+/- heterozygote, were functionally hemizygous at the glk locus. A model is proposed, similar to that for the mutational events at the adenine phosphoribosyl transferase locus (W. E. C. Bradley and D. Letovanec, Somatic Cell Genet. 8:51-66, 1982), of two different events, high and low frequency, being responsible for mutation at either of the linked loci tk and glk. The low-frequency event may be a point mutation, but the high-frequency event, in many instances, involves coordinated inactivation of a portion of a chromosome carrying the two linked alleles. Class II heterozygotes would be generated as a result of a low-frequency event at one allele, and class I heterozygotes would be generated by a high-frequency event. Supporting this model was the demonstration that all class I glk+/- lines examined were functionally hemizygous at tk.

Comprehensive Analysis of Production Loggings in Fuling Shale Gas Play in China

2021 ◽  
Author(s):  
Yaowen Liu ◽  
Wei Pang ◽  
Jincai Shen ◽  
Ying Mi
Keyword(s):  
Shale Gas ◽  
Mineral Content ◽  
Horizontal Wells ◽  
Organic Content ◽  
Gas Production ◽  
Liquid Loading ◽  
Comprehensive Overview ◽  
Gas Field ◽  
Well Trajectory ◽  
Positive Effect

Abstract Fuling shale gas field is one of the most successful shale gas play in China. Production logging is one of the vital technologies to evaluate the shale gas contribution in different stages and different clusters. Production logging has been conducted in over 40 wells and most of the operations are successful and good results have been observed. Some previous studies have unveiled one or several wells production logging results in Fuling shale gas play. But production logging results show huge difference between different wells. In order to get better understanding of the results, a comprehensive overview is carried out. The effect of lithology layers, TOC (total organic content), porosity, brittle mineral content, well trajectory is analyzed. Results show that the production logging result is consistent with the geology understanding, and fractures in the favorable layers make more gas contribution. Rate contribution shows positive correlation with TOC, the higher the TOC, the greater the rate contribution per stage. For wells with higher TOC, the rate contribution difference per stage is relatively smaller, but for wells with lower TOC, it shows huge rate contribution variation, fracture stages with TOC lower than 2% contribute very little, and there exist one or several dominant fractures which contributes most gas rate. Porosity and brittle minerals also show positive effect on rate contribution. The gas rate contribution per fracture stage increases with the increase of porosity and brittle minerals. The gas contribution of the front half lateral and that of latter half lateral are relatively close for the "upward" or horizontal wells. However, for the "downward" wells, the latter half lateral contribute much more gas than the front half lateral. It is believed that the liquid loading in the toe parts reduced the gas contribution in the front half lateral. The overview research is important to get a compressive understanding of production logging and different fractures’ contribution in shale gas production. It is also useful to guide the design of horizontal laterals and fractures scenarios design.

Advanced Well Completion Strategies to Improve Gas Production Deliverability in Marginal Tight Gas Reservoirs from an Onshore Abu Dhabi Gas Field

2021 ◽  
Author(s):  
Hajar Ali Abdulla Al Shehhi ◽  
Bondan Bernadi ◽  
Alia Belal Zuwaid Belal Al Shamsi ◽  
Shamma Jasem Al Hammadi ◽  
Fatima Omar Alawadhi ◽  
...  
Keyword(s):  
Hydraulic Fracturing ◽  
Horizontal Wells ◽  
Gas Production ◽  
Abu Dhabi ◽  
Tight Gas ◽  
Production Rates ◽  
Well Productivity ◽  
Gas Saturation ◽  
Well Design ◽  
The Impact

Abstract Reservoir X is a marginal tight gas condensate reservoir located in Abu Dhabi with permeability of less than 0.05 mD. The field was conventionally developed with a few single horizontal wells, though sharp production decline was observed due to rapid pressure depletion. This study investigates the impact of converting the existing single horizontal wells into single long horizontal, dual laterals, triple laterals, fishbone design and hydraulic fracturing in improving well productivity. The existing wells design modifications were planned using a near reservoir simulator. The study evaluated the impact of length, trajectory, number of laterals and perforation intervals. For Single, dual, and triple lateral wells, additional simulation study with hydraulic fracturing was carried out. To evaluate and obtain effective comparisons, sector models with LGR was built to improve the simulation accuracy in areas near the wellbore. The study conducted a detailed investigation into the impact of various well designs on the well productivity. It was observed that maximizing the reservoir contact and targeting areas with high gas saturation led to significant increase in the well productivity. The simulation results revealed that longer laterals led to higher gas production rates. Dual lateral wells showed improved productivity when compared to single lateral wells. This incremental gain in the production was attributed to increased contact with the reservoir. The triple lateral well design yielded higher productivity compared to single and dual lateral wells. Hydraulic fracturing for single, dual, and triple lateral wells showed significant improvement in the gas production rates and reduced condensate banking near the wellbore. A detailed investigation into the fishbone design was carried out, this involved running sensitivity runs by varying the number of branches. Fishbone design showed considerable increment in production when compared to other well designs This paper demonstrates that increasing the reservoir contact and targeting specific areas of the reservoir with high gas saturation can lead to significant increase in the well productivity. The study also reveals that having longer and multiple laterals in the well leads to higher production rates. Hydraulic fracturing led to higher production gains. Fishbone well design with its multiple branches showed the most production again when compared to other well designs.

Simultaneous Hydraulic Fracturing Improves Completion Efficiency and Lowers Costs Per Foot

2021 ◽  
Author(s):  
David Russell ◽  
Price Stark ◽  
Sean Owens ◽  
Awais Navaiz ◽  
Russell Lockman
Keyword(s):  
Hydraulic Fracturing ◽  
Oil And Gas ◽  
Horizontal Wells ◽  
Asset Returns ◽  
Gas Production ◽  
Well Performance ◽  
Additional Time ◽  
Oil And Gas Production ◽  
Single Well ◽  
Lateral Length

Abstract Reducing well costs in unconventional development while maintaining or improving production continues to be important to the success of operators. Generally, the primary drivers for oil and gas production are treatment fluid volume, proppant mass, and the number of stages or intervals along the well. Increasing these variables typically results in increased costs, causing additional time and complexity to complete these larger designs. Simultaneously completing two wells using the same volumes, rates, and number of stages as for any previous single well, allows for more lateral length or volume completed per day. This paper presents the necessary developments and outcomes of a completion technique utilizing a single hydraulic fracturing spread to simultaneously stimulate two or more horizontal wells. The goal of this technique is to increase operational efficiency, lower completion cost, and reduce the time from permitting a well to production of that well—without negatively impacting the primary drivers of well performance. To date this technique has been successfully performed in both the Bakken and Permian basins in more than 200 wells, proving its success can translate to other unconventional fields and operations. Ultimately, over 200 wells were successfully completed simultaneously, resulting in a 45% increase in completion speed and significant decrease in completion costs, while still maintaining equivalent well performance. This type of simultaneous completion scenario continues to be implemented and improved upon to improve asset returns.

Plug and Abandonment Environment in British Columbia

2019 ◽  
Author(s):  
Majid Bizhani ◽  
Élizabeth Trudel ◽  
Ian Frigaard
Keyword(s):  
British Columbia ◽  
Fractured Reservoirs ◽  
Horizontal Wells ◽  
Gas Production ◽  
Vertical Wells ◽  
Gas Industry ◽  
Testing Procedures ◽  
The Past ◽  
Production Wells ◽  
Well Abandonment

Abstract British Columbia (BC) has a significant oil & gas industry, with approximately 25,000 wells drilled in the province since the early 1900s. In the past few decades, the industry has changed from a balanced oil & gas production to activities dominated by unconventional gas production which is recovered by hydraulic fracturing. Concurrently, since 2000 there has been a shift from isolated vertical wells to pad-drilled horizontal wells. The older well stock at end-of-life combines with horizontal production wells and fractured reservoirs, the consequence of which is a growing wave of abandonment in BC, building over the next decade. This paper reviews the existing data on BC wells, as it is relevant to well abandonment operations. This includes the well architectures, trajectories, depths, testing procedures, etc.

scholarly journals Water-Gas Two-Phase Flow Behavior of Multi-Fractured Horizontal Wells in Shale Gas Reservoirs

Processes ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 664 ◽  
Author(s):  
Lei Li ◽  
Guanglong Sheng ◽  
Yuliang Su
Keyword(s):  
Organic Matter ◽  
Shale Gas ◽  
Flow Behavior ◽  
Horizontal Wells ◽  
Gas Production ◽  
Phase Flow ◽  
Gas Reservoirs ◽  
Two Phase ◽  
Fractured Horizontal Wells ◽  
Water Gas

Hydraulic fracturing is a necessary method to develop shale gas reservoirs effectively and economically. However, the flow behavior in multi-porosity fractured reservoirs is difficult to characterize by conventional methods. In this paper, combined with apparent porosity/permeability model of organic matter, inorganic matter and induced fractures, considering the water film in unstimulated reservoir volume (USRV) region water and bulk water in effectively stimulated reservoir volume (ESRV) region, a multi-media water-gas two-phase flow model was established. The finite difference is used to solve the model and the water-gas two-phase flow behavior of multi-fractured horizontal wells is obtained. Mass transfer between different-scale media, the effects of pore pressure on reservoirs and fluid properties at different production stages were considered in this model. The influence of the dynamic reservoir physical parameters on flow behavior and gas production in multi-fractured horizontal wells is studied. The results show that the properties of the total organic content (TOC) and the inherent porosity of the organic matter affect gas production after 40 days. With the gradual increase of production time, the gas production rate decreases rapidly compared with the water production rate, and the gas saturation in the inorganic matter of the ESRV region gradually decreases. The ignorance of stress sensitivity would cause the gas production increase, and the ignorance of organic matter shrinkage decrease the gas production gradually. The water film mainly affects gas production after 100 days, while the bulk water has a greater impact on gas production throughout the whole period. The research provides a new method to accurately describe the two-phase fluid flow behavior in different scale media of fractured shale gas reservoirs.

Design of Sand Washing and Plug Removal Device with High Pressure Foam Fluid Jet

2012 ◽  
Vol 155-156 ◽  
pp. 722-725
Author(s):  
Wen Bin Cai ◽  
Guo Wei Qin ◽  
Yan He
Keyword(s):  
High Pressure ◽  
Oil And Gas ◽  
Horizontal Wells ◽  
Gas Production ◽  
Oil Field ◽  
Good Effect ◽  
Well Bore ◽  
Sand Production ◽  
Oil And Gas Production ◽  
And Performance

In the oil and gas production process, serious sand production causes reservoir and pipe blocked, which makes productivity declined, even stopped. It's the efficient means of sand washing and plug removal by using high-pressure foam fluid jet. The structure and performance of sand washing device determines the efficiency of sand washing and plug removal. The device's nozzle consists of anti-blocking valves, three kinds of nozzles with self-drive, rotation characteristics during the operation. The nozzles include sand washing nozzle, couple nozzle and power nozzle. This device can be used in horizontal wells with complex well bore situation to carry out sand and plug removal. The device has a good effect on sand washing and plug removal in the oil field.

Research and Application of the Deep Horizontal Drilling and Completion Technology for Liaohe Oilfield Buried Hill Reservoir

2012 ◽  
Vol 241-244 ◽  
pp. 1396-1399
Author(s):  
Gui Min Nie ◽  
Dan Guo ◽  
Yan Wang ◽  
Xiao Wei Cheng
Keyword(s):  
Oil And Gas ◽  
Drilling Fluid ◽  
Horizontal Wells ◽  
Gas Production ◽  
Oil Field ◽  
Oil And Gas Production ◽  
Horizontal Drilling ◽  
Liaohe Oilfield ◽  
Buried Hill ◽  
Composite Drilling

With the depletion of shallow-layer oil and gas pools inLiaohe oilfield, buried hill stratigraphic reservoirs in Liaohe oil field are becoming main objectives for exploration in recent years, especially in high-risk areas of Xinglongtai deep the Hing ancient buried hill resources are particularly rich. Since 2007, Liaohe oilfield increased investment for Buried Hill reservoirs with deep horizontal drilling developt the buried hill reservoir. Liaohe has completed 36 deep horizontal, with a total footage of 183920m, the average depth of 5109m. Improving drilling speed of "buried hill deep horizontal and branch horizontal wells”, and reducing drilling costs are of great urgency. “Hing buried hill deep horizontal, horizontal wells,” with composite drilling technology, supporting the optimization of PDC bits, the high-pressure jet drilling, the MWD borehole trajectory control and optimization of drilling parameters, the new drilling fluid technology and so on. With a large number of horizontal wells put into Buried Hill stratigraphic reservoirs, oil and gas production of average deep horizontal well increase of 2-5 times. Besides, the previous recovery and production of oil and gas reservoirs significantly improved to create an objective economic and social benefits.

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