Medium Reservoir Research Articles

Key Techniques of Tertiary Oil Recovery in Medium and Low Permeability Reservoirs Based on Computer Display Technology

Oil is a kind of non-renewable energy. Our demand for oil is on the increase. With the continuous exploitation of oil resources, China’s oil reserves gradually decrease. As a result, China imports a lot of crude oil every year. With the exploitation of oil, China’s large oil fields will gradually dry up, which requires China to develop medium and low permeability reservoirs. However, there are many difficulties in the development of medium and low permeability reservoirs, such as dense matrix, complex fracture system and low permeability, which will lead to low recovery. With the development of science and technology and the combination of computer technology, eor technology has gradually matured and can be used in low and medium permeability reservoirs. In this paper, the technology of eor is analyzed firstly. Then, according to the characteristics of low and medium permeability reservoirs shown by the computer, the fracturing, percolation, enhanced oil recovery technology and microbial oil displacement technology are analyzed to better develop low and medium permeability reservoirs.

Realtime Cost and Performance Improved Reservoir Simulator Service using ANN and Cloud Containers

Real time reservoir simulation is growing demand while drilling to find new energy resources. Especially during drilling when the test data differs from actual data due to fault injections. This paper proposes a methodology using modified ANN scheduler using task characteristics and optimal cloud containers. Our methodology optimizes cost and end to end delay to achieve real time reservoir simulations. Realization of the paper is done using azure cloud resources and open porous media (OPM) reservoir simulator code. ANN based scheduling of cloud containers make the simulator energy efficient and scalable. Methodology uses microservice based architecture which gives the advantage of real time modifications, pluggability with minimum validation costs. Patent is demonstrated on 3-phase black oil well reservoirs - Input pod, Grid pod, Solver pods, Upscale pods, Output pods, 3D PODs. ANN scheduler with Ant Colony Optimization (ACO) will classify the input tasks based on task characteristics and schedule the POD containers on the optimal virtual machines (VMs). Proposed architecture is realized using Kubernetes docker containers on Microsoft azure linux VMs.

Reservoir classification and evaluation of Yan'an formation in Xifeng Oilfield

According to reservoir lithology and the combination of pore throat, this paper takes porosity, permeability, pore throat diameter and displacement pressure as evaluation parameters to classify and evaluate the reservoir. Yan'an Formation reservoir in Xifeng Oilfield is divided into four types, I, II, III and IV, which correspond to four types of good, medium, poor and non reservoir respectively.From class I to class IV reservoir, the reservoir performance changes from good to bad, the porosity and permeability decrease, and the heterogeneity increases. The results of geological analysis show that the classification results are reasonable and have certain guiding significance for the exploration and development of oil and gas in the oilfield.

Study on induced stress of hydraulic fracturing in fractured‐porous elastic media

AbstractThe study on induced stress of hydraulic fracturing is an important part of hydraulic fracturing design, temporary plugging and steering fracturing design, and completion design in oil and gas development. Based on fracture continuum method (FCM), cohesive unit method, and finite volume method (FVM), the propagation behavior of multiple hydraulic fractures (HFs) in fractured‐porous media reservoir is simulated from the perspective of fluid and geological stress coupling. The influence of natural fractures (NFs) on stress distribution and stress inversion sensitive factors are studied. NFs in the model are equivalent to physical models controlled by tension and shear bonds. The proposed model can deal with any number of NFs, which greatly improves the computational efficiency of the model. Then PKN analytic solution and Abaqus software results were used to verify the correctness of our model. The results show that the NF will make the reservoir stress show strong heterogeneity after fracturing, and the prominent feature is the regional stress mutation. The sudden change of stress shows the sudden increase or decrease in stress; with the increase in the initial stress difference, the stress inversion becomes more difficult. When the stress difference exceeds 3 MPa, the stress inversion area is almost 0. The stress interference increases with the decrease in cluster spacing. The stress inversion region between HFs decreases, while the external stress inversion region increases; Biot coefficient has great influence on stress and stress inversion. With the decrease in Biot coefficient, stress inversion region will decrease obviously. When the Biot coefficient is 0.4, there is no stress inversion area in the whole reservoir. Poisson's ratio has little influence on stress inversion. When Poisson's ratio changes between 0.1 and 0.3, the change range of stress is within 1 MPa, and the stress inversion area is almost unchanged. Our results can be helpful for understanding the stress distribution after hydraulic fracturing in fractured‐porous media.

Formation conditions and exploration direction of large and medium gas reservoirs in the Junggar Basin, NW China

Abstract The Junggar Basin is rich in oil but lacks natural gas, which is inconsistent with its geological background of natural gas. Based on the analysis of main source kitchens, and the evaluation of geological setting and controlling factors of gas accumulation, it is proposed that three significant fields for gas exploration should be emphasized. The first field is the Carboniferous volcanic rocks. The Carboniferous residual sags and large-scale reservoirs were developed in three active continental margins, i.e., the southeastern, northeastern and northwestern active continental margins. Gas accumulation is controlled by the favorable reservoir-caprock combinations composed of volcanic rocks and their superimposed lacustrine mudstones in the Upper Wuerhe Formation. Dinan, Eastern and Zhongguai uplifts are three favorable directions for natural gas exploration. The second field is the Lower combinations in the southern margin of Junggar Basin. Rows of structural traps were developed in this area with ideal preservation conditions and space-time configuration for trap-source combinations. Sets of clastic reservoirs and overpressured mudstones formed perfect reservoir-caprock combinations which are the main exploration direction for Jurassic coal-type gas reservoirs in this area. The seven large structural traps in the middle-east section are recently the most significant targets. The last field is the Central Depression. Large hydrocarbon generating centers, i.e., Mahu, Fukang and Shawan sags, were developed in this area, their source rocks were deeply buried and at highly-mature stage. Thus the Central Depression is a favorable exploration direction for Permian high-over mature gas fields (reservoirs). Great attentions should be paid to two types of targets, the deeply–buried structures and structural-lithologic traps. Based on three main gas systems, gas exploration is suggested be strengthened within three fields and on three levels.

Oil oxidation in the whole temperature regions during oil reservoir air injection and development methods

Abstract The oil oxidation characteristics of the whole temperature regions from 30 °C to 600 °C during oil reservoir air injection were revealed by experiments. The whole oil oxidation temperature regions were divided into four different parts: dissolving and inflation region, low temperature oxidation region, medium temperature oxidation region and high temperature oxidation region. The reaction mechanisms of different regions were explained. Based on the oil oxidation characteristics and filed tests results, light oil reservoirs air injection development methods were divided into two types: oxygen-reducing air flooding and air flooding; heavy oil reservoirs air injection in-situ combustion development methods were divided into two types: medium temperature in-situ combustion and high temperature in-situ combustion. When the reservoir temperature is lower than 120 °C, oxygen-reducing air flooding should be used for light oil reservoir development. When the reservoir temperature is higher than 120 °C, air flooding method should be used for light oil reservoir development. For a normal heavy oil reservoir, when the combustion front temperature is lower than 400 °C, the development method is medium temperature in-situ combustion. For a heavy oil reservoir with high oil resin and asphalting contents, when the combustion front temperature is higher than 450 °C, the development method at this condition is high temperature in-situ combustion. Ten years field tests of air injection carried out by PetroChina proved that air has advantages in technical, economical and gas source aspects compared with other gas agents for oilfield gas injection development. Air injection development can be used in low/super-low permeability light oil reservoirs, medium and high permeability light oil reservoirs and heavy oil reservoirs. Air is a very promising gas flooding agent.

Biomarker hydrocarbons of oils from the Labagan field of the Timan-Pechora oil and gas province

The results of geochemical studies of four oils samples from Paleozoic deposits of the Labagan field of the Timan-Pechora oil and gas province are presented. It is shown that the organic matter, which generated the oil of the Lower Devonian and Tournaisian deposits of the Labagan field, is sapropelic, its accumulation occurred in a marine sub-reducing environment. The oils of the Artinskian and Ufimian deposits are substantially biodegraded. Type of collectors is fissure-porous, secondary-porous. Carbonate reservoirs of the Devonian, Carboniferous and Permian (Artinian) age are characterized by good and medium reservoir properties. Terrigenous reservoirs of the Ufimian deposit have good reservoir properties.

Numerical pressure transient analysis for unfilled-caved carbonate reservoirs based on Stokes-Darcy coupled theory

Caved carbonate reservoirs are very special because of the strong heterogeneity. The pressure transient behavior of the caved carbonate reservoirs is quite different from the conventional homogeneous or dual medium reservoirs because of the presence of large-scale cavities. There are two types of cavities: filled and unfilled, which dominated the production of the reservoirs. Fluid flow in the unfilled cavity should be described by Stokes' equation rather than Darcy's law. It is needed to better understand the role of the unfilled cavities plays in the pressure transient analysis. The objective of this work is to analyze the pressure transient behavior of the unfilled cavities. A coupled Stokes-Darcy pressure transient model is developed and the finite element method is applied in the solutions of the mathematical models. Then, the numerical pressure transient model is used in the analysis of two typical cases: a well drilled into the unfilled cavity (WIC) and a well not drilled into the unfilled cavity (WOC). The type curves of the WIC model indicate that flow in the unfilled cavity is an oscillated pressure-drop rather than a radial flow. The unfilled cavity that the well drilled into would be considered as an enlarged wellbore which is equivalent to a negative skin factor, as a consequence the wellbore storage coefficient will increase. Main characteristics of type curves for WOC model are the valley on the pressure derivative. A cavity with a larger size and smaller distance from the wellbore would give rise to a deeper valley. Comparative results indicate that unfilled cavities described by the Stokes' equation are not the limit of the filled cavities with extremely large mobility, which was predicted by previous work.

Electrofacies analysis of the Asmari reservoir, Marun oil field, SW Iran

This article integrates core and well log data to determine reservoir electrofacies of the Oligo-Miocene Asmari Formation in the western Dezfol Embayment, SW Iran. At the start, an unsupervised neural network was employed based on the selforganizing map (SOM) technique to identify and extract electrofacies groups of Asmari Formation in the Marun oilfield, which is a mixed siliciclastic and carbonate reservoir. Using inexpensive and accessible petrophysical wireline logs, such as gamma ray, sonic, density and neutron, along with calculated reservoir data (water saturation and effective porosity) from 12 reference wells and their correlation with reservoir core data, led to recognition of seven electrofacies including first four class as limestone rocks (EF1–EF4) and others three classes as sandstone rocks (EF5–EF7). Based on the porosity and permeability maps and water saturation at different depth levels, EF4 and EF7 with low porosity and permeability, high water saturation are considered as non-reservoir relating mostly to sedimentary textures of mudstone and argillaceous sandstones, respectively. By contrast, EF1 and EF5 with high values of porosity, permeability and low percent of water saturations characterize the best reservoir quality rocks, and EF2, EF3 and EF6 have medium reservoir quality. EF1 consists of dolomitic skeletal grainstone, in which biomoldic, vuggy and intercrystalline porosity is the dominant pore type, while the intergranular porosity is the major pore type in EF4 as an unconsolidated sand electrofacies. In general, the results obtained in this study indicate a satisfactory agreement between core data and log facies. This correlation allows rockfacies to be classified in the cored wells and predict those facies in the uncored wells. Using the methodology outlined here, it is possible to track reservoir electrofacies from conventional well log data.

Study on Validation of the OPM Reservoir Simulator by Comparative Solution Project

The Open Porous Media (OPM) reservoir simulation toolkit is a free and open-source development in the reservoir simulation world and one that has received very little attention. OPM Flow is a fully-implicit, black-oil simulator capable of running industry-standard simulation models, which encourage open innovation and reproducible research on modeling and simulation of porous media processes. This study validates and assesses the capabilities of OPM Flow comparing with the industry standard ECLIPSE simulator. Several tests were conducted in order to validate the simulator, including a zero- balance test, symmetrical well test, three simulation models based on the SPE Comparative Solution Project, and a real world dataset from the Norne oilfield in Norway. This variety of tests covers a wide range of reservoir types and specific operating conditions which are representative of expected applications of the software. By comparison it is concluded that OPM Flow reservoir simulator can be considered a validated and capable reservoir simulator that is able to compete with Schlumberger ECLIPSE in many cases and shows great potential for future development. In addition, a basic user interface for queuing and running simulations through the OPM Flow simulator was developed using the Python programming language as well as some modifications to the miscible flooding solver.

Fish farming in cages: a practice to be restricted in Brazil

Abstract: World aquaculture has been growing sharply in recent decades and Brazilian production of fish in cages has grown considerably since the end of the 1990s. This increase is related to the development of federal government regulations and the large number of medium and large hydroelectric reservoirs. The main areas of fish production in cages in Brazil are currently located in the Northeast and Southeast regions and along the Southeast/South border. Tilapia production in cages in Brazil, as well as other species produced in cages in other regions of the world, has economic advantages for the producer. On the other hand, limnologically, tilapia production in cages causes enormous damage, as it promotes the process of artificial eutrophication and, possibly, introduces this exotic species. One way of reducing artificial eutrophication is the use of Integrated Multi-trophic Aquaculture (IMTA); however, its use in fish cages installed in Brazilian reservoirs is not possible yet. Therefore, our view is that government agencies restrict the production of fish in cages to the utmost.

Layer-specific cell differentiation in bi-layered vascular grafts under flow perfusion

Bioengineered grafts have the potential to overcome the limitations of autologous and non-resorbable synthetic vessels as vascular substitutes. However, one of the challenges in creating these living grafts is to induce and maintain multiple cell phenotypes with a biomimetic organization. Our biomimetic grafts with heterotypic design hold promises for functional neovessel regeneration by guiding the layered cellular and tissue organization into a native-like structure. In this study, a perfusable two-compartment bioreactor chamber was designed for the further maturation of these vascular grafts, with a compartmentalized exposure of the graft’s luminal and outer layer to cell-specific media. We used the system for a co-culture of endothelial colony forming cells and multipotent mesenchymal stromal cells (MSCs) in the vascular grafts, produced by combining electrospinning and melt electrowriting. It was demonstrated that the targeted cell phenotypes (i.e. endothelial cells (ECs) and vascular smooth muscle cells (vSMCs), respectively) could be induced and maintained during flow perfusion. The confluent luminal layer of ECs showed flow responsiveness, as indicated by the upregulation of COX-2, KLF2, and eNOS, as well as through stress fiber remodeling and cell elongation. In the outer layer, the circumferentially oriented, multi-layered structure of MSCs could be successfully differentiated into vSM-like cells using TGFβ, as indicated by the upregulation of αSMA, calponin, collagen IV, and (tropo)elastin, without affecting the endothelial monolayer. The cellular layers inhibited diffusion between the outer and the inner medium reservoirs. This implies tightly sealed cellular layers in the constructs, resulting in truly separated bioreactor compartments, ensuring the exposure of the inner endothelium and the outer smooth muscle-like layer to cell-specific media. In conclusion, using this system, we successfully induced layer-specific cell differentiation with a native-like cell organization. This co-culture system enables the creation of biomimetic neovessels, and as such can be exploited to investigate and improve bioengineered vascular grafts.

ОПТИМИЗАЦИЯ ПАРАМЕТРОВ НЕОРГАНИЧЕСКОГО АГЕНТА УПРАВЛЕНИЯ ПРОФИЛЕМ НА ОСНОВЕ СИЛИКАТА НАТРИЯ ДЛЯ ЭФФЕКТИВНОГО ВЫТЕСНЕНИЯ НЕФТИ ИЗ КОЛЛЕКТОРОВ С ВЫСОКОЙ МИНЕРАЛИЗАЦИЕЙ

Актуальность. В настоящее время нефтяное месторождение Туха является месторождением со средней, низкой проницаемостью и с высокоминерализованной пластовой водой. Обводненность основного продуктивного пласта на участке «Y» месторождения Туха составляет более 93 %, поэтому необходимо применять эффективные технологии для повышения коэффициента извлечения нефти. Существующие полимеры, в том числе и солеустойчивые, не могут хорошо растворяться и распределяться в пластовой воде, обладают слабой способностью удерживания в пласте, управления потоком, поэтому трудно быстро достичь хорошего экономического эффекта от их внедрения. В связи с этим актуальной задачей является разработка метода управления профилем для эффективного вытеснения нефти из коллекторов с высокой минерализацией. Цель: исследование эффективности вытеснения нефти и оптимизация параметров неорганического агента управления профилем на основе силиката натрия для повышения нефтеотдачи пластов. Методы. Определение вязкости исследуемых образцов проводили на вискозиметре Брукфилда DV-II, эксперименты исследования влияния размера оторочек главного агента, количества циклов альтернативного заводнения, скорости закачки главного агента и закачки поверхностно-активного вещества на эффективность вытеснения нефти были проведены на фильтрационной установке. Результаты. Для повышения нефтеотдачи пластов на месторождении Туха на основе геологических характеристик пласта и флюидных свойств участка «Y» были проведены исследования по оптимизации параметров и увеличению эффективности вытеснения нефти неорганическим агентом на основе силиката натрия для управления профилями. Результаты показали, когда размер оторочек основного агента изменяется от 0,06 до 0,08 Vзач/Vпор и количество циклов альтернативного заводнения составляет 5–6, степень использования слоев со средней и низкой проницаемостью более высокая, обводненность значительно уменьшается и коэффициент извлечения нефти значительно увеличивается. По сравнению с одиночным силикатным заводнением сочетание силиката натрия и поверхностного активного вещества может повысить объем охвата и коэффициент извлечения нефти.

Stable H-O Isotopic Composition and Water Quality Assessment of Surface Water and Groundwater: A Case Study in the Dabie Mountains, Central China.

In order to understand the water cycle and assess the water quality for irrigation purposes in the Upper Pi River Basin (UPRB), which is the northern slope of the Dabie Mountains, 68 surface water and groundwater samples were collected and analyzed for H-O isotopes and hydrochemistry during the high-flow season in 2017 and 2018. The results show that ranges of hydrogen and oxygen isotopic composition (δ2H: −68.8‰ to −40.8‰, δ18O: −10.05‰ to −5.05‰) are controlled by the medium latitude and high altitude of the UPRB. Among different types of water, the δ2H and δ18O values can be ordered as follows: reservoir water < spring water ≈ river water < pond water. The water of the upstream medium and small reservoir is enriched with lighter isotopes that is likely related to more exchange with rainwater and less residence time; however, large reservoirs are similar to the upstream river and spring in terms of the H-O isotopic composition. Hydro-chemical facies are dominated by the Ca-HCO3 type in the UPRB, which reflects fresh recharged water from rainfall, and few samples are of the Ca-Cl type that is caused by intensive evaporation. The water quality for irrigation purposes was also evaluated. According to the Wilcox diagram, United States Salinity Laboratory (USSL) diagram, magnesium hazard, and Kelly’s ratio, all water samples have been considered suitable for irrigation water.

Comparative analysis of pore structure and fractal characteristics of micropores in medium and high rank coals——Taking the typical mining area of western Guizhou and eastern Yunnan as an example

In order to clarify the micropore pore structure characteristics of medium and high rank coal reservoirs, based on low temperature CO2 adsorption test and surface/volume fractal theory, the structure and fractal characteristics of medium and high coal rank micropores (0.40∼2nm) were analyzed. The results show that with the increase of coal metamorphism, the pore size of coal reservoirs changes from 0.55∼0.8nm to 0.5∼0.7nm, and the pore size is 0.5∼0.9nm. Microporous pores have good fractal characteristics, Dav1<Dav2 indicating stage the pore volume heterogeneity increases with the pore size in the pore range. Dav2 is positively correlated with the maximum vitrinite reflectance, indicating that the pore volume heterogeneity increases with the pore size in the micropore range. The heterogeneity of the surface area of the adsorption pore is far more complicated than the volume heterogeneity, Das1< Das2⩾Das3, indicating that the surface heterogeneity of the micropore decreases with the decrease of the pore size and tends to be stable; As the degree of metamorphism of coal increases. And the study shows that the influence of coal rank on surface heterogeneity decreases with the decrease of pore size.

Reservoir accumulation conditions and key exploration & development technologies for Keshen gas field in Tarim Basin

The Keshen gas field is located in the central part of Kuqa foreland thrust belt in Tarim Basin, and is another large gas field discovered in Kuqa depression after Kela 2 gas field. Since the breakthrough in 2008, a number of large and medium scale gas reservoirs including Keshen 2, Keshen 5 and Keshen 8 have been discovered, that are characterized by ultra depth, ultra-high pressure, ultra-low porosity, ultra-low permeability, high temperature and high pressure. With natural gas geological reserves of nearly trillion cubic meters and production capacity of nearly 5.5 billion cubic meters, the Keshen gas field is the main natural gas producing area in Tarim Oilfield. The Keshen gas field is located in a series of thrusting imbrication structures in the Kelasu structural belt of Kuqa foreland thrust belt. The salt roof structure, plastic rheology of salt beds and pre-salt faulted anticlinal structure constitute the large wedge-shaped thrust body. The thick delta sandstone of the Cretaceous Bashijike Formation is widely distributed, and it forms the superior reservoir-caprock combination with overlying Paleogene thick gypsum-salt bed. The deep Jurassic-Triassic oil and gas migrate vertically along fault system formed in Late Himalaya, break through the thick Cretaceous mudstone and move laterally along the fracture system of the pre-salt reservoirs, to form anticline and fault anticline high pressure reservoir groups. Through near ten years of studies, the three-dimensional seismic acquisition and processing technology for complex mountainous areas, extrusion salt-related structural modeling technology and fractured low-porosity sandstone reservoir evaluation technology have been established, which lay a foundation for realization of oil and gas exploration objectives. Logging acquisition and evaluation technology for high temperature, high pressure, ultra-deep and low-porosity sandstone gas reservoirs, and efficient development technology for fractured tight sandstone gas reservoirs have been developed, which provide a technical support for efficient exploration & development and rapid production of the Keshen gas field.

Seismic damage analysis and reinforcement measure research for earth dams after a strong earthquake

At present, there are more than 98,000 reservoirs and dams in China. Most of these projects are earth dams. As unexpected disasters and events occur frequently, emergency response problems facing reservoirs and dams are increasingly prominent. Especially during a strong earthquake, the dangerous problems of these dams will be more serious, which is a serious threat to people’s lives and property downstream. Therefore, the seismic damages and the measures of reinforcement need to be studied. Basic data of 379 reservoirs were at high-risk or at dam-break risk, as well as the damage situations of medium and small earth dams damaged in the Wenchuan earthquake, are collected and presented in this paper. Several main failure modes of earth dams during the earthquake are analyzed and summarized. For practical engineering, some reinforcement measures for the typical failure mode of an earth dam are also proposed. The Wenjiajiao earth dam, a typical medium reservoir in the high-risk category, located in Cangxi County, Sichuan Province, is selected as the analysis example. The dam safety and seismic stability are calculated and analyzed by the finite element software program ANSYS. The results indicate that the biggest permanent deformation caused by the earthquake occurred in the dam crest; the maximum deformation is mainly a downward subsidence of 21.8 cm. As the thickness of the dam top part decreases, the dynamic displacement and vibration velocity of the dam crest increases. This calculation is consistent with the actual situation where the parapet wall of a dam crest was seriously incline and the upper slope collapsed and cracked. The research results can provide a reference for the danger control and reinforcement of similar earthquake damaged reservoirs.

Bone-chip system to monitor osteogenic differentiation using optical imaging.

Human organoids and organ-on-chip systems to predict human responses to new therapies and for the understanding of disease mechanisms are being more commonly used in translational research. We have developed a bone-chip system to study osteogenic differentiation in vitro, coupled with optical imaging approach which provides the opportunity of monitoring cell survival, proliferation and differentiation in vitro without the need to terminate the culture. We used the mesenchymal stem cell (MSC) line over-expressing bone morphogenetic protein-2 (BMP-2), under Tet-Off system, and luciferase reporter gene under constitutive promoter. Cells were seeded on chips and supplemented with osteogenic medium. Flow of media was started 24 h later, while static cultures were performed using media reservoirs. Cells grown on the bone-chips under constant flow of media showed enhanced survival/proliferation, comparing to the cells grown in static conditions; luciferase reporter gene expression and activity, reflecting the cell survival and proliferation, was quantified using bioluminescence imaging and a significant advantage to the flow system was observed. In addition, the flow had positive effect on osteogenic differentiation, when compared with static cultures. Quantitative fluorescent imaging, performed using the osteogenic extra-cellular matrix-targeted probes, showed higher osteogenic differentiation of the cells under the flow conditions. Gene expression analysis of osteogenic markers confirmed the osteogenic differentiation of the MSC-BMP2 cells. Immunofluorescent staining performed against the Osteocalcin, Col1, and BSP markers illustrated robust osteogenic differentiation in the flow culture and lessened differentiation in the static culture. To sum, the bone-chip allows monitoring cell survival, proliferation, and osteogenic differentiation using optical imaging.

Research on Parallel Reservoir Perforation Technology

The parallel reservoir perforating technology enables each shot hole in the gun to be fired in a direction parallel to the reservoir at a set angle, realizing a new technique in which the perforating projectile and the reservoir are parallel. The technology can be combined with the azimuth perforating technology. For the oblique angle of the reservoir and the wellbore, the oil pipe conveying type azimuth perforating technology, the inclined well self-orientation perforating technology and the modular cable perforating technology can be used for construction. The technology can effectively reduce the fracture pressure of reservoir construction, improve the productivity of medium and low permeability reservoir oil wells, and meet the needs of low permeability, thin poor layer and special well development and transformation.

DISTRIBUTION CHARACTERISTICS AND CONTROL FACTORS OF HYDROGEN SULFIDE IN XISHAN COAL MINE OF SOUTHERN MARGIN OF JUNGGAR BASIN IN CHINA

The regional structure of Xishan coal mine, located in the binding site of southern margin of Junggar basin and northern mountain Tianshan, belongs to the foothill fault-fold structural belt of southern margin of Junggar Basin. Most the coal seams which were formed by continental facies are in the range of medium-extra low sulfur and part of the coal seams belong to high sulfur coal. The hydrogen sulfide in coal seam concentrate anomaly and distribute very unevenly, with the maximum value of H 2 S up to 2.11%. The gas composition in coal bed mainly are N 2 and CH 4 , components H 2 S, CO 2 , C 2 H 6 , C 3 H 8 and another heavy hydrocarbon. The mirror reflectance of coal is generally between 0.5% to 0.7%. The abundant source rocks are the strong material basis for the formation of H 2 S. The pore structure of coalbed belongs to the fracture-pore type. The medium and better reservoir have a wide range of distribution. The proportion of roof microclastic rocks and floor microclastic rocks of coal seam is up to 75% and 87% respectively. These factors are conducive to the enrichment of H 2 S. The thick aquifer formed in the sag basement, under the control of hydrodynamic block gas, provides a huge space of occurrence and migration for groundwater and H 2 S. Along the runoff direction, the salinity, pH value and H 2 S content in regional groundwater gradually increase. The water is rich of sulfate ion, reflecting a closed well of regional deep confined water. In sufficient organic matter and reducing environment, the hydrogen sulfide will come into being in the role of BSR or TSR.