scholarly journals Study on reasonable nozzle size after volumetric fracturing of glutenite reservoir

2020 ◽  
Vol 165 ◽  
pp. 03007
Author(s):  
Shi Le ◽  
Li Ruochen ◽  
Luo Gan ◽  
Gu Li Za Dan-Mao Lahong ◽  
Li Bin ◽  
...  
Keyword(s):  
Drainage System ◽  
Rate Of Change ◽  
Small Displacement ◽  
Systematic Research ◽  
Well Test ◽  
Stable Production ◽  
Production Practice ◽  
Volume Fracturing ◽  
Reasonable Choice ◽  
Volumetric Fracturing

What kind of drainage system should be adopted after the volumetric fracturing of the glutenite reservoir in the Mahu 1 well area, lack of systematic research. The reasonable choice of the size of the nozzle is the key to determining the flow back of the fracturing fluid and stable production. By comparing the applicability differences of fracturing and drainage systems at home and abroad, this paper analyzes the production experience of neighboring areas and determines the overall principles of drainage system: small displacement principle, stable drainage principle and step-by-step amplification principle. Then, by calculating the rate of change of oil production, analyzing the system well test curve and production curve, and determining a reasonable drainage system, it is concluded that the volume of the glutenite reservoir after fracturing should be 1.5 mm small nozzle, and the pressure is gradually stabilized. The grade is replaced by a 2.5 mm nozzle. Most of the wells are finally stabilized in the 3.0 mm nozzle production. A small number of wells can be properly enlarged to a 3.5mm nozzle for stable production. Under the guidance of this understanding, the horizontal wells in the Mahu 1 well area have basically reached the design capacity, providing theoretical basis and guidance for the production practice after volume fracturing.

The Performance Evaluation of Old Well after SRV in Ordos Basin Tight Oil Reservoir

2014 ◽  
Author(s):  
H.. Wang ◽  
X.. Liao ◽  
H.. Ye ◽  
X.. Zhao ◽  
C.. Liao ◽  
...  
Keyword(s):  
Evaluation Method ◽  
Ordos Basin ◽  
Fracture Network ◽  
Water Flooding ◽  
Tight Oil ◽  
Oil Reservoir ◽  
Well Test ◽  
Stimulated Reservoir Volume ◽  
Tight Oil Reservoir ◽  
Volume Fracturing

Abstract The technology of Stimulated reservoir volume (SRV) has been the key technology for unconventional reservoir development, it can create fracture network in formation and increase the contact area between fracture surface and matrix, thus realizing the three-dimensional stimulation and enhancing single well productivity and ultimate recovery. In China, the Ordos Basin contains large areas of tight oil reservoir with the porosity of 2~12 % and permeability of 0.01~1 mD. The most used development mode is conventional fracturing and water flooding, which is different from the natural depletion mode in oversea, but the development effect is still unfavorable. The idea of SRV is proposed in nearly two years in Changqing Oilfield. SRV measures are implemented in some old wells in tight oil formation. It is a significant problem that should be solved urgently about how to evaluate the volume fracturing effect. Based on the real cases of old wells with SRV measures, the microseismic monitoring is used to analyze the scale of formation stimulation and the complexity of fracture network after volume fracturing; the numerical well test and production data analysis (PDA) are selected to explain the well test data, to analyze the dynamic data, and to compare the changes of formation parameters, fluid parameters and plane streamlines before and after volume fracturing; then the interpretation results of well test with the dynamic of oil and water wells are combined to evaluate the stimulation results of old wells after SRV. This paper has presented a set of screening criteria and an evaluation method of fracturing effect for old well with SRV in tight oil reservoir. It will be helpful to the selection of candidate well and volume fracturing operation in Ordos Basin tight oil reservoir. It should be noted that the evaluation method mentioned in the paper can be expanded to volume stimulation effect evaluation in other unconventional reservoirs, such as tight gas, shale gas and so on.

Rational Production Proration of Gas Wells in Unconsolidated Sandstone Gas Reservoir

2011 ◽  
Vol 121-126 ◽  
pp. 1249-1253
Author(s):  
Guo Yun Wu ◽  
Jiao Li
Keyword(s):  
Well Test ◽  
Gas Reservoir ◽  
Gas Recovery ◽  
Water Influx ◽  
Water Breakthrough ◽  
Stable Production ◽  
Single Well ◽  
Rational Production ◽  
Set Up

Multi-layered unconsolidated sandstone gas reservoir is featured by unconsolidated lithology, interbeded gas-water zones and active edge water. Irrational production proration will lead to water breakthrough and sand inflow(AOF) is already incompetent in solving problems nowadays. Based on multipoint well test deliverability analysis, production data dynamic analysis, single well controlled reserves and critical situation of inflow calculation, and combining the calculation of minimum liquid hold-up gas rate an maximum erosion gas rate, meanwhile considering balanced gas recovery factor, balanced pressure drop, safe sand inflow and safe liquid hold-up, the multi-factor production plan has been set up, which is improved and adjusted by integrating water influx performance and years of stable production, through gas reservoir numerical simulation. A scientific and rational production proration pattern particularly for this type of gas reservoir has been determined. The reservoir simulation results of case study show that the water production in gas well can be controlled and the gas reservoir sustained stable production can last more than 1.3 year.

A Solution for Mechanical Isolation Volume Refracturing in Ultra-Low Permeability Horizontal Wells: A Case Study in Ordos Basin

2021 ◽  
Author(s):  
Zhiguo Wang ◽  
Zhongneng Liu ◽  
Jie Gui ◽  
Hai'en Yang ◽  
Yong Ren ◽  
...  
Keyword(s):  
Large Volume ◽  
Ordos Basin ◽  
Field Tests ◽  
Horizontal Wells ◽  
Low Permeability ◽  
Effective Measure ◽  
Stable Production ◽  
Volume Fracturing ◽  
Mechanical Isolation ◽  
Reliable Solution

Abstract With the rise of volume fracturing concept and its application in new wells, it has been shown that increasing fracturing volume is an effective measure to improve production and achieve long-term stable production of ultra-low permeability reservoirs in Ordos Basin. However, refracturing requires running liner, which makes the flow passage smaller and can't reach the volume of new wells. The challenge is how to design the tubing combination and develop matching tools to further improve refracturing volume in 5.5″ casing. The objectives of this study are to design a combined mechanical isolation liner and carry out fine-staged large-volume refracturing with a rate of 8 m3/min in 5.5″ casing. In this study, researchers have designed the liner, optimized refracturing tools and wellhead equipment by comprehensively considering reservoir pressure, wellbore, available tubing combinations and friction of fracturing fluid. Downhole microseismic technology is used to monitor refracturing microseismic events, and high-precision 3D scanning technology is used to detect and analyze the wall wear of liners after refracturing. Field tests have been carried out in Ordos ultra-low permeability horizontal wells and achieved perfect effect. This research provides a reliable solution and technical reserve for volume refracturing of ultra-low permeability reservoir in horizontal wells, and verifies that large-volume plays an important role in improving refracturing effect in the test area.

On the one-dimensional approximations to the quantum mechanics of π -electrons in chain and ring systems

1969 ◽  
Vol 313 (1514) ◽  
pp. 403-419 ◽  
Keyword(s):  
Beltrami Operator ◽  
Rate Of Change ◽  
Transverse Motion ◽  
Critical Examination ◽  
Small Displacement ◽  
Free Electrons ◽  
Mechanical Motion ◽  
One Dimensional ◽  
The One ◽  
Special Case

A critical examination is made of the one-dimensional approximations for the quantum mechanical motion of almost-free electrons confined near a general space curve. A special set of coordinates which separate the longitudinal from the transverse directions for the general curve are introduced to specify the motion. The Laplace-Beltrami operator is found and Schrödinger’s equation is investigated when the transverse motion is limited to a small displacement. The special case where the curve has isolated sharp kinks is shown to be soluble in terms of certain boundary conditions at the points of large rate of change of curvature. When the curvature varies slowly the transition energies are shown to follow from the onedimensional longitudinal approximation to a certain order in the transverse displacements. However, the absolute energies are strongly dependent on the transverse motions.

scholarly journals Injury Patterns among Forestry Workers in Croatia

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1356
Author(s):  
Matija Landekić ◽  
Ivan Martinić ◽  
David Mijoč ◽  
Matija Bakarić ◽  
Mario Šporčić
Keyword(s):  
Forest Management ◽  
Average Rate ◽  
Statistical Significance ◽  
Injury Rate ◽  
Forest Harvesting ◽  
Rate Of Change ◽  
Systematic Research ◽  
Significant Difference ◽  
Workplace Accidents ◽  
Manual Felling

Timber harvesting, especially motor-manual felling, in Croatia, as in many other countries, is one of the most hazardous economic activities. Consequently, the aim of this paper is to analyse and compare the latest trends and risk factors related to the incidence of work-induced injuries in structural organization units of national forest enterprise. A combined approach of literature review and assembled secondary data was applied to gather data on workplace accidents over the years 2014–2020. Work-induced injuries data were drawn from the records of the national enterprise Croatian Forests Ltd. which manages state forests (76% of total forest area). A total of 1626 work-induced injuries were processed and entered into the database. Data analysis was conducted using statistical and descriptive methods. Research results have proven a significant difference in the injury rate over the years 2014–2020 in the Croatian forest enterprise. During the analysed period the highest number of workplace accidents (51.35% of all recorded workplace accidents) occurred during the forest harvesting phase, i.e., during motor-manual felling. Trends in the incidence of work-induced injuries in the observed period do not show any significant improvement. The key findings have pointed out that forest administrations which practice even-aged forest management have 25% or more injuries than forest administrations which practice selective forest management. Related to the average rate of change by forest administration, the largest annual increase or decrease of the selected safety indicators is recorded for smallest forest administrations. Related to total number of injuries, the smallest forest administrations have the least injuries and show statistically significant difference compared to large forest administrations. When comparing the number of injuries per 1000 employees, medium sized forest administrations have the highest value of indicator and show statistical significance. Discussion and conclusion of the paper emphasizes the need for systematic research in the field of ergonomy, safety and health of forest workers in Croatian forestry sector. Additionally, the development and inclusion of proactive safety culture is recognized as a mechanism that can further reduce work injuries and improve occupational safety which should have a significant role in the process of certification of forest management according to the FSC standard.

scholarly journals Research on numerical method for evaluation of vertical well volume fracturing effect based on production data and well test data

2021 ◽  
Vol 11 (4) ◽  
pp. 1855-1863
Author(s):  
Debin Xia ◽  
Zhengming Yang ◽  
Daolun Li ◽  
Yapu Zhang ◽  
Xinli Zhao ◽  
...  
Keyword(s):  
Numerical Model ◽  
Test Data ◽  
Fracture Zone ◽  
Fracture Network ◽  
Production Data ◽  
Well Test ◽  
Vertical Wells ◽  
Equivalent Permeability ◽  
Main Fracture ◽  
Volume Fracturing

AbstractVolume transformation technology has become a key technology for developing low-permeability/tight oil and gas reservoirs. Evaluating the post-fracturing effect is very important for the development plan formulation and fracturing plan evaluation. In this paper, the vicinity of the main fracture is divided into the main fracture zone and the secondary fracture zone. The main fracture with infinite conductivity and the branch fracture with increased permeability are used to describe the transformation area. Based on this physical model, a numerical model considering the nonlinear seepage characteristics of the reservoir, stress sensitivity, wellbore storage and skin effects was established. Based on this numerical model, a comprehensive evaluation method for the fracturing effect of volume modification of vertical wells based on well test data and production data was established and this method was applied to three typical vertical wells. The results show that conventional vertical fracturing vertical wells can only form a single primary fracture and the range of equivalent permeability increase is very small. Volume fracturing can form a fracture network composed of primary fractures and secondary fractures, and increase the equivalent permeability of the fracture network area. The fracture half-length, equivalent permeability and reconstruction area of the volume fracturing well are dynamically changing and gradually decrease with the increase in production time and the fracturing effect becomes weak until it fails.

A Device for Magnification Measurement

1972 ◽  
Vol 30 ◽  
pp. 622-623
Author(s):  
J.A. Eades ◽  
A. van Dun
Keyword(s):  
Electron Microscope ◽  
Small Displacement ◽  
Private Communication ◽  
Piezoelectric Crystal ◽  
Double Exposure ◽  
Standard Methods ◽  
Elegant Method ◽  
The Right ◽  
Piezo Electric

The measurement of magnification in the electron microscope is always troublesome especially when a goniometer stage is in use, since there can be wide variations from calibrated values. One elegant method (L.M.Brown, private communication) of avoiding the difficulties of standard methods would be to fit a device which displaces the specimen a small but known distance and recording the displacement by a double exposure. Such a device would obviate the need for changing the specimen and guarantee that the magnification was measured under precisely the conditions used.Such a small displacement could be produced by any suitable transducer mounted in one of the specimen translation mechanisms. In the present case a piezoelectric crystal was used. Modern synthetic piezo electric ceramics readily give reproducible displacements in the right range for quite modest voltages (for example: Joyce and Wilson, 1969).

Observation of faint contrast at planar faults in alloys

1978 ◽  
Vol 36 (1) ◽  
pp. 340-341
Author(s):  
K. Kuroda ◽  
Y. Tomokiyo ◽  
T. Kumano ◽  
T. Eguchi
Keyword(s):  
Reciprocal Lattice ◽  
Beam Theory ◽  
Al Alloys ◽  
Small Displacement ◽  
Electron Microscopic ◽  
Lattice Vector ◽  
Fringe Contrast ◽  
Planar Fault ◽  
Lattice Displacement ◽  
The Many

The contrast in electron microscopic images of planar faults in a crystal is characterized by a phase factor , where is the reciprocal lattice vector of the operating reflection, and the lattice displacement due to the fault under consideration. Within the two-beam theory a planar fault with an integer value of is invisible, but a detectable contrast is expected when the many-beam dynamical effect is not negligibly small. A weak fringe contrast is also expected when differs slightly from an integer owing to an additional small displacement of the lattice across the fault. These faint contrasts are termed as many-beam contrasts in the former case, and as ε fringe contrasts in the latter. In the present work stacking faults in Cu-Al alloys and antiphase boundaries (APB) in CuZn, FeCo and Fe-Al alloys were observed under such conditions as mentioned above, and the results were compared with the image profiles of the faults calculated in the systematic ten-beam approximation.

Superstructures and ordering phenomena in ceramic superconductors

1996 ◽  
Vol 54 ◽  
pp. 710-711
Author(s):  
R. Gronsky
Keyword(s):  
Domain Growth ◽  
Small Displacement ◽  
Small Scale ◽  
Ceramic Superconductors ◽  
Oxygen Sublattices ◽  
Tweed Contrast ◽  
Diffraction Patterns ◽  
Representative Image ◽  
Static Lattice ◽  
Modulation Wavelength

It is now well established that the phase transformation behavior of YBa2Cu3O6+δ is significantly influenced by matrix strain effects, as evidenced by the formation of accommodation twins, the occurrence of diffuse scattering in diffraction patterns, the appearance of tweed contrast in electron micrographs, and the generation of displacive modulation superstructures, all of which have been successfully modeled via simple Monte Carlo simulations. The model is based upon a static lattice formulation with two types of excitations, one of which is a change in oxygen occupancy, and the other a small displacement of both the copper and oxygen sublattices. Results of these simulations show that a displacive superstructure forms very rapidly in a morphology of finely textured domains, followed by domain growth and a more sharply defined modulation wavelength, ultimately evolving into a strong <110> tweed with 5 nm to 7 nm period. What is new about these findings is the revelation that both the small-scale deformation superstructures and coarser tweed morphologies can result from displacive modulations in ordered YBa2Cu3O6+δ and need not be restricted to domain coarsening of the disordered phase. Figures 1 and 2 show a representative image and diffraction pattern for fully-ordered (δ = 1) YBa2Cu3O6+δ associated with a long-period <110> modulation.

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