Lithologic Reservoirs

In order to clarify some misunderstandings of shale gas, the occurrence state of shale gas was studied. Shale is a type of rock consisting of matrix mudstone and micro sandslices, which is heterogeneous mudstone with stratification structures. Sandslices are microscopic and poorly continuous, which are the micro traps of lithology in shale. The methane generated in matrix of shale migrates a short distance into sandsilces and accumulates and forms reservoirs. Shale gas is free gas stored in micro sandslices. There is no adsorption gas in shale matrix and sandslices. Shale gas reservoirs are not continuous reservoirs, which consist of numerous micro gas reservoirs. There is no connection between micro gas reservoirs. The development of shale gas needs to use horizontal wells with multiple macrofracturing which can connect mirco gas reservoirs as more as possible. Because there is only one component of methane in shale gas, the concept of concentration is not appropriate and the diffusion phenomenon cannot take place in shale gas development. Gas flow driven by pressure difference is the main mechanism of shale gas production. Shale gas reservoirs are typical single-pore media, but not dual-pore media.

Accumulation models and numerical models of tight oil:A case study from Yanchang Formation in Ordos Basin

GUO Qiulin，CHEN Ningsheng，SONG Huanqi，WU Xiaozhi，XIE Hongbing

2013, Vol.25(1): 4–10 Abstract ( 703 ) PDF (653 KB) ( 798 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.002

Tight oil can be divided into shale oil, sandwich type tight oil and adjacent source type tight oil. According to their geological characteristics and accumulation mechanism, the accumulation models were established. The result shows that: ① the shale oil accumulation process is very special, it neither experienced second migration nor primary migration, only experienced initial migration; ② sandwich type tight oil belongs to self-generation and self-accumulation, and it is the result of primary migration; ③ adjacent source type tight oil is a kind of transitional reservoirs, its migration is different from primary and second migration, and it is the driving result of “expansion force”. Based on this understanding, this paper proposed the “expanded flow” driving theory, and established adjacent source type tight oil numerical model, sandwich type tight oil numerical model based on self-generation and self-accumulation, and the volumetric method model of shale oil numerical calculation. Application example proves that this technique has a good prospect of application.

Research progress on the propagation and linkage of faults

QUE Xiaoming

2013, Vol.25(1): 11–15 Abstract ( 379 ) PDF (390 KB) ( 388 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.003

Growth faults normally act as the boundary faults along basins, and control the evolution of basins. The characters of fault growth, revealed by articles abroad, are based on the increase of displacement and length. Quantitative constraints from ancient fault systems show mainly two models. Conventional growth models suggest that faults become larger due to systematic increase in both maximum displacement and length, which predict a systematic power-law relationship between maximum displacement （D） and maximum trace length （L） of the form D= cLn.Others suggest alternative growth models, in which faults are rapidly lengthening at an initial short stage, followed by a subsequent longer phase by increasing cumulative displacement at roughly constant length. It is a significant process in controlling the size and shape of many sedimentary basins in extensional settings that the evolution and linkage of fault segments to form continuous fault zones. This paper discussed these fault growth models and the characters of fault linkage by summarizing the research findings.

Research progress on simulation of microscopic remaining oil

PAN Shaowei， LIANG Hongjun， LI Liang， LUO Haining, WANG Jiahua

2013, Vol.25(1): 16–20 Abstract ( 513 ) PDF (246 KB) ( 748 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.004

Many scholars have carried out the research on the simulation of microscopic remaining oil in order to develop the underground petroleum resources further. Firstly, this paper gave the simulation of microscopic remaining oil definition and elaborated the research situation home and abroad. Secondly, pointed out the existing deficiencies of the current simulation of microscopic remaining oil on four aspects: the great difference between the experimental environment and the real underground environment, the ignorance on the wettability of the rock, the research only completed in the two-dimensional space and the inaccurate representation of the reservoir microscopic pore structure. Thirdly, summarized the studies on the simulation of microscopic remaining oil in our country, and put forward six suggestions on the future development for the simulation of microscopic remaining oil, which are to improve the physical experiment, use the fractal geometry theory and CT technology, combine with the actual geologic features and establish the complete theoretical system. The simulation of microscopic remaining oil is of great significance for the revelation of the microscopic remaining oil distribution, therefore various viewpoints about the simulation of microscopic remaining oil were reviewed in order to provide reference for the future research.

A query to the concept of top-water reservoir

ZHU Suyang， LI Chuanliang

2013, Vol.25(1): 21–23 Abstract ( 574 ) PDF (242 KB) ( 460 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.005

Because shale cap rocks can be clearly found for some heavy oil reservoirs, the top-water reservoir concept was proposed to explain the phenomena. The concept of top-water reservoir is lack of scientific principle, which is easy to make reservoir engineering misunderstood. In order to correct the concept, a study was made to analyze the sealing mechanism of cap rocks, which concludes that cap rocks are not necessarily shale rocks, and all rocks with poor physical properties can be cap rocks. Top-water reservoirs are not without cap rocks, they are only with no shale cap rocks, but they have physical property cap rocks to seal oil and gas. The oil and water distribution in this kind of reservoirs is still normal. In order to prevent misunderstanding reservoir engineering, the top-water reservoir concept should not be used any more.

Trace fossils and sedimentary environment of the Upper Triassic Xujiahe Formation in Sichuan Basin

JIN Hui， ZHANG Jun， MA Shiyu

2013, Vol.25(1): 24–28 Abstract ( 527 ) PDF (488 KB) ( 499 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.006

The Upper Triassic Xujiahe Formation in Sichuan Basin has abundant trace fossils. In accordance with ecological and behavior features of trace makers, these fossils can be classified into three categories, including trace fossils of animals with clear shape, escape structures and Rhizolithos （predominantly fibrous Rhizolithos）. Trace fossils of animals with clear shape can be classified into ten species in seven genera in three categories （including two species indeterminata）, namely, ① Domichnia. Skolithos linearis, S.verticalis, Arenicolites ichnosp., Cylindrium ichnosp., Ophiomorpha nodosa; ②Fodinichnia. Planolites beverleyensis, P.montanus, Palaeophycus tubularis, and P.striatus;③Pascichnia. Cochlichnus anguineus. Most of trace makers for these trace fossils can be classified as arthropod （especially insecta）. There are also a small quantity of mollusks （predominantly gastropods and bivalves） and worms. They are preserved in fine sandstones, siltstones or silty mudstones as full relief and epirelief. In accordance with distribution of trace fossils and analyses of sedimentary environments, three ichnofabrics can be identified：①Cochlichnus-Planolites ichnofabric, which is predominantly composed of fodinichnia and pascichnia, formed in sedimentary environments of supratidal mudflat with swamps developed locally; ②Cylindricum-Planolites ichnofabric, which is dominated by dwelling burrows and feeding burrows. High abundance and diversity of trace fossils may reflect their sedimentary environment of intertidal zone; ③ Skolithos linearis ichnofabric, which is dominated by long, vertical or high-angle dwelling burrows of suspension feeders, formed in subtidal zone, in which energies in surrounding water changed periodically with changes in relative sea levels.

Sedimentary facies of Triassic-Jurassic formation in Yuqi area, Tarim Basin

ZHONG-LIANG Xuanzi， FU Heng， LIU Yanting， CHEN Ji

2013, Vol.25(1): 29–34 Abstract ( 636 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.007

Based on detailed field outcrop profiles and the core drilling observation, combining with the rock color, sedimentary structures, profile structures, log facies and seismic response, the sedimentary facies of Triassic-Jurassic formation in Yuqi area of Tarim Basin was analyzed, which is wet fan delta-lacustrine sedimentary system. The time and space evolution analysis result shows that during Triassic to Jurassic, the climate is humid, and the main sources come from the southern margin of Shaya uplift. There are two set of complete depositional cycles in Triassic formation, which are wet fan delta and lake. And due to the tectonic uplift of Indosinian movement, the top of Triassic formation and the Upper-Middle Jurassic formation are absent. Wet fan delta plain is developed in the Lower Jurassic formation. The research results are useful to understand the depositional environment during the period of Triassic to Jurassic, and can provide basic geologic data for oil and gas exploration in this area.

Lithofacies paleogeography and sand bodies distribution of the Upper Jurassic Suining Formation in the middle section of western Sichuan Depression

LIU Anran，CHEN Hongde，XU Shenglin，ZHAO Junshou

2013, Vol.25(1): 35–39 Abstract ( 531 ) PDF (396 KB) ( 427 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.008

Guided by the high-resolution sequence stratigraphy theory, and making the middle-term cyclic sequence as mapping unit, this paper studied the paleogeography and sand body distribution characteristics. The result shows that the Upper Jurassic Suining Formation in the middle section of western Sichuan Depression can be divided into one longterm sequence （LSC1） and three middle-term sequences （MSC1-MSC3）. The front of Longmen Mountain developed alluvial fan group, and braided river delta deposition is manifested in multiple braided river delta overlay during the period of the MSC1-MSC3. The depositions are mainly of braided river delta-lacustrine deposition during the period of the MSC1-MSC2, alluvial fan only changed in the size and location, and sand bodies mainly distributed in the front of Longmen Mountain and Zhongjiang-Huilong area. During the period of M3, the deposition changed into thick and large-scale braided river delta plain deposition, and sand bodies mainly distributed in Pixian-Wenjiang-Dayi area.

Diagenesis of the eighth member of Shihezi Formation in Dingbian area, Ordos Basin

ZHANG Li， YANG Shengu， YANG Rui， PAN Lina

2013, Vol.25(1): 40–44 Abstract ( 483 ) PDF (468 KB) ( 493 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.009

Based on the analysis of casting slice, scanning electron microscope and X-ray diffraction, this paper studied the characteristics of lithology and diagenesis of the eighth member of Shihezi Formation in Dingbian area. The result shows that the main sand bodies in this area are lithic sandstone and lithic quartz sandstone, and the compositional maturity is high and the textural maturity is medium. The sandstone is in the B stage of middle diagenetic stage. The early compaction pressolution and cementation are destructive for the reservoir properties, while the secondary pores formed by dissolution are constructive for the reservoir properties. The study of diagenesis can provide theoretical criterion for reservoir evaluation and prediction.

High resolution sequence stratigraphy of the second member of Xujiahe Formation in Tongnan area, central Sichuan Basin

LIU Xiaoliang， WANG Chaoyong

2013, Vol.25(1): 45–50 Abstract ( 503 ) PDF (612 KB) ( 508 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.010

Guided by the sedimentology and high resolution sequence stratigraphy theory, in combination with the data of outcrop profile, drilling core and well logging, this paper studied the high resolution sequence stratigraphy of the second member of Xujiahe Formation in the central Sichuan Basin. On the basis of recognition of different levels sequence interfaces and the types of lake flooding surface, Xujiahe Formation can be divided into two middle-term base level cyclical sequences （MSC） and four short-term base level cyclical sequences （SSC）. Among the short-term base level cyclical sequences （SSC）, we identified two cyclical structures, which are asymmetry form deepening upwards （A form） and symmetric form deepening upwards then getting shallow again（C form）. Making the short-term base level cycle as the time unit, the ancient geographical characteristics and evolution of the second member of Xujiahe Formation were discussed in detail, and the influence of lateral migration of drainage line on the sedimentary facies was analyzed.

Xujiaweizi Depression Time and space matching relation between gas source faults and cap rocks and its controlling action on gas accumulation: An example from

FU Guang， ZHANG Chaoqun

2013, Vol.25(1): 51–55 Abstract ( 477 ) PDF (545 KB) ( 513 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.011

Based on the study of development of gas source faults and cap rocks, active state of fault and formation period of sealing ability, time and space matching relation between gas source faults and cap rocks and its controlling action on gas accumulation in Xujiaweizi Depression were studied. The result shows that the space matching relation between gas source faults and mudstone cap rocks of K1d2 is good, but the space matching relation between gas source faults and volcanic cap rocks on the top of K1yc1 is bad. The time matching relations of gas source faults with mudstone cap rocks of K1d2 and volcanic cap rocks on the top of K1yc1 is good. The space matching relation between gas source faults and cap rocks influences the gas accumulation layer and location, while the time matching relation between gas source faults and cap rocks influences the gas accumulation degree.

Fluvial sand bodies distribution and evolution of He 8 member in Su 14 block of Sulige Gas Field

BAI Zhenhua，ZHAN Yantao，WANG Ying，ZENG Liyuan

2013, Vol.25(1): 56–62 Abstract ( 512 ) PDF (712 KB) ( 644 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.012

The fluvial sand bodies are characterized by rapid lateral facies variation, weak continuity and connectivity and strong reservoir heterogeneity, which seriously affect the development of the fluvial reservoir. Based on the study of the reservoir sedimentology, the fluvial sand bodies distribution and evolution of He 8 member in Su 14 block were studied. The result shows that the sedimentary background in the He 8 member is gradual transition from the early braided river deposition to the later meandering river deposition, and the sedimentary microfacies mainly includes channel lag deposits, channel bars, point bars, crevasse splays, natural levees, overbank sand and mud deposits. By the influence of the interaction between the base level and the sediment supply, the fluvial evolution experienced three stages, which are the braided river prosperous development stage, the braided river and meandering river coexistence and transforming stage and the meandering river prosperous development stage. The sand bodies of channel bar and point bar in the stage of the braided river prosperous development and the braided river and meandering river coexistence and transforming are the main gas-bearing reservoirs. The development of favorable gas-bearing sand bodies is controlled by sedimentary microfacies and base level cycles.

Reservoir characteristics of Jurassic in Yuka-Jiulongshan area,northern margin of Qaidam Basin

WU Zhixiong，ZHANG Yongshu，ZOU Kaizhen，WANG Mu， DU Zhongming，SHI Ji’an

2013, Vol.25(1): 63–68 Abstract ( 526 ) PDF (582 KB) ( 398 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.013

By means of cores, cast thin sections, scanning electron microscope and testing data, this paper studied the reservoir pore structure characteristics of Jurassic in Yuka-Jiulongshan area in northern margin of Qaidam Basin, and analyzed the controlling factors of reservoir development. The result shows that the reservoir spaces in the study area are mainly primary intergranular pores, dissolved pores and microfractures, among which dissolved pores are dominated and play important role in improving the reservoir properties. The reservoir mainly experienced such actions as compaction, cementation and dissolution. Especially the cementation and dissolution are the main reason of generating the secondary pore in Yuka-Jiulongshan area.

Diagenesis of Chang 6 reservoir of Upper Triassic in Jiyuan area,Ordos Basin

CHENG Jun， LI Hong， LEI Chuan

2013, Vol.25(1): 69–74 Abstract ( 432 ) PDF (556 KB) ( 490 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.014

The Chang 6 reservoir of Upper Jurassic in Jiyuan area is characterized by poor physical properties, complicated diagenesis, strong heterogeneity and low permeability. Based on the analysis of cast thin section, cathode luminescence and scanning electronic microscope, the diagenesis of Chang 6 reservoir was studied. The result shows that sandstone reservoirs in this area are mainly composed of fine lithic arkose and feldspathic sandstone, mainly developed intergranular pores and intragranular dissolved pores, mainly experienced compaction, cementation, dissolution and metasomatism, and the diagenetic evolution reached the middle diagenetic stage A. The diagenesis of Chang 6 reservoir is the main controlling factor for reservoir properties. This study can provide basic data and guidance for the oil and gas exploration and development in this area.

Geochemical characteristics of hydrocarbon source rocks of the Lower Cretaceous in the Chagan Sag

LIU Jun，LUO Xiaoping，LI Hui，LI Xinjun

2013, Vol.25(1): 75–80 Abstract ( 471 ) PDF (581 KB) ( 835 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.015

Lacustrine dark mudstones of the lower Cretaceous Bayinggebi Formation and Suhongtu Formation are the main hydrocarbon source rocks in the Chagan Sag. This paper revealed the geochemical characteristics of the source rocks on the basis of the abundance, types and maturity of organic matter and biomarker analysis. The results show that hydrocarbon source rocks have high abundance of organic matter and belong to good hydrocarbon source rocks, and the type of organic matter belongs to transition type. The organic matter type of Bayinggebi Formation is superior to that of Suhongtu Formation. The former is mainly of Ⅱ1- Ⅱ2, while the latter is mainly of Ⅱ2- Ⅲ. The organic matter of the hydrocarbon source rocks has a high degree of thermal evolution and is at maturity stage, even a high-post maturity stage. The hydrocarbon source rocks occurred in the weak oxidation-weak reducing environment, and the organic source material is mainly lower aquatic plants mixed with some higher plants.

Types and characteristics of reefs of Permian Changxing Formation around Kaijiang-Liangping trough, eastern Sichuan Basin

ZHOU Gang， ZHENG Rongcai， LUO Ren， LIU Huayi， WEN Huaguo

2013, Vol.25(1): 81–87 Abstract ( 558 ) PDF (586 KB) ( 631 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.016

Platform-edge reef flat facies is the most important oil and gas exploration layer of Changxing Formation around Kaijiang-Liangping trough, eastern Sichuan Basin. The lithology of the reservoir is mainly reef flat facies crystal dolomites, and it has the characteristics of broad distribution areas, great thickness and fine physical properties. Through the observation of outcrop, core and thin section, this paper studied the internal structures and development characteristics of platform-edge reefs in the study area. The result shows that the platform-edge reefs have very different sedimentary characteristics in different places near the trough, and could be divided into patch reefs and mound reefs according to the development scales. Because of the different palaeogeomorphology and sea-level change，the patch reefs and mound reefs possess different evolution stages and reservoir characteristics. The patch reefs developed with the characteristics of shorter formation time, thinner reservoir thickness and poor properties, while the mound reefs mainly developed with the characteristics of larger formation time, thicker reservoir thickness and fine properties. Platform-edge reefs reservoir belongs to low porosity and low permeability reservoir. As a kind of the platform edge reefs, the mound reefs reservoir is better than that of patch reefs, and the patch reefs reservoir developed in the second period of Changxing Formation is better than patch reefs reservoir developed in the first period of Changxing Formation.

Application of joint inversion technique to prediction of favorable reservoirs: A case study from Aer Sag

WANG Menghua，QIN Fengqi，WANG Ya，ZHANG Jing，ZHANG Lingyan，LIU Haoqiang

2013, Vol.25(1): 88–94 Abstract ( 485 ) PDF (672 KB) ( 523 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.017

Aer Sag is characterized by multi-provenance, near-provenance, narrow facies belt and rapid facies change. The sand bodies present longitudinal stack and cross-binding, and the distribution of permeable sand bodies is complicated, so it is difficult to ascertain the distribution of the favorable reservoirs, which seriously affects the calculation of reserves. This paper carried out the fine reservoirs prediction by using joint inversion technique, and determined the thickness variation trend and the distribution range of permeable sand bodies. The result of calculation measures up to requirement of reserve calculating, which provides major parameters and references for the calculation of the proven reserves. The actual application proves that using joint inversion technique to predict permeable sand bodies can obtain a high accuracy and meet the demands of reserves calculation for oilfield.

Reverse-time migration analysis of several seismic observation models

CHEN Keyang

2013, Vol.25(1): 95–101 Abstract ( 435 ) PDF (534 KB) ( 781 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.018

This paper analyzed the applicability of the seismic wave pre-stack reverse-time migration technology on the migration of data from different seismic observation models, such as surface seismic, borehole seismic and cross well seismic. Taking velocity model with different dip angle and Marmousi velocity model as examples, we synthesized several common shot gathers corresponding to observation models, and carried out numerical experiments on reverse time migration further. The results show that the reverse-time migration method is suitable for these seismic observation models, and can get perfect imaging results; the S/N ratio can be further improved by low-frequency noise suppression method. The direct wave and refracted wave of the surface seismic observation model must be finely cut, and the first arrival wave field （down propagating direct wave） must be preserved of the borehole seismic and cross well seismic observation model. In this way, the wave field energy transformation relation between the reflection and transmission can be remained unchanged, and it can depict detailed features the geological structure to a maximum extent.

Recognition of compacted sandstone gas reservoirs of Tai 2 member in Daniudi Gas Field

WU Juanjuan，LI Zhongdong，CHEN Wei，LIU Dong

2013, Vol.25(1): 102–106 Abstract ( 436 ) PDF (332 KB) ( 612 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.019

The second member of Taiyuan Formation in Daniudi Gas Field belongs to typical compacted gas-bearing sandstone reservoir with low porosity and low permeability. Due to its low porosity, low permeability and strong heterogeneity, it is difficult to identify and evaluate the gas reservoir. According to the fact that lithology controls the physical properties, and physical properties control gas-bearing characteristics in the tight sandstone reservoir, the lithology, physical properties and electrical properties of Tai 2 member were analyzed. The result shows that Tai 2 member belongs to compacted gas-bearing sandstone reservoirs with low porosity and low permeability. Based on logging data, the interpretation parameter model was established. The crossplots of open flow capacity with acoustic travel time, deep lateral resistivity, shale content, porosity and gas saturation were respectively used to identify the effective gas-bearing layers, and its recognition standard was established. The log interpretation resulted from test layers of 23 development wells were used to test the standard of the effective gas reservoir with an interpretation coincidence rate of 86.96%. It proves the validity of the proposed method.

Calculation of permeability in igneous rock formation based on Stoneley wave

YAN Wei，ZHANG Chong，HU Ting，PAN Xiuping

2013, Vol.25(1): 107–110 Abstract ( 510 ) PDF (265 KB) ( 600 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.020

Igneous reservoir is characterized by dual porosity. Permeability calculation is one of the difficulties in volcanic reservoir evaluation. In order to enhance the accuracy of permeability calculation, Stoneley wave, compression wave and shear wave were picked out from the dipole shear wave image logging. In combination with borehole diameter, formation density and porosity curve, the theoretical Stoneley moveout was calculated. The difference between the measured Stoneley moveout and the calculated theoretical Stoneley moveout is defined as qualitative indicator of fluid mobility which can indicate the permeability and pore connectivity of reservoir and validation of fracture. The relationship between the qualitative indicator of fluid mobility and the total effective permeability can be used to estimate igneous formation permeability. The actual application in deep igneous rock of Songliao Basin proves the validity of this method.

Study on sandstone transport system of the upper part of the fourth member of Shahejie Formation in Gao 89 block of Boxing Subsag

ZHAO Jianhua1， ZENG Jianhui2，3， ZHANG Yongwang2，3， HUANG Lili1

2013, Vol.25(1): 111–115 Abstract ( 457 ) PDF (425 KB) ( 494 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.021

Sandstone transport system, as one of the main hydrocarbon transport system, is very important for hydrocarbon migration in Boxing Subsag. Based on the geologic setting, combined with the data of seismic, well drilling cores, formation test, logging and analysis testing, the geological modeling method was applied to establish the 3D isochronous stratigraphic framework model of Es41 in Gao 89 block. Then the sand body distribution map was drawn by sedimentary facies modeling, and porosity model and permeability model were established under the constraint of sedimentary facies. At last, by analyzing sand body connectivity and reservoir property limit, it is considered that the reservoir properties of the sand group 1 of Chunxia sub-member are better than others. Sand bodies near Gao 89, Fan 142 and Fan 5-3 wells are favorable transport systems and hydrocarbon accumulation areas.

Study on spectral modeling deconvolution in time-frequency domain

DIAO Rui， SHANG Xinmin， RUI Yongjun， GANG Mingchuan， LIU Guanghua

2013, Vol.25(1): 116–121 Abstract ( 490 ) PDF (636 KB) ( 884 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.022

The energy of seismic wave attenuates continuously in spreading process, and its effective band of frequency amplitude spectrum is striation, which declines the resolution of seismic data. Improved generalized S transform of window function normalized energy holds time resolution constant，and improves the frequency resolution at the same time. Spectral modeling method is drawn in time-frequency domain, in order to avoid the complex window dimension program of the Fourier transform. Spectral modeling method is adapted to the assumption condition that seismic data are smooth and steady signals. Through model experiment and actual seismic data processing, it is proved that this method can improve the resolution of seismic data effectively, which is favorable for thin reservoir identification and fine reservoir description.

A new method to judge liquid loading of gas wells in tight gas field of Daniudi area

ZHAO Jie， LI Yingchuan1， LIU Tong， ZHOU Junjie， ZHANG Di， ZHONG Bowen

2013, Vol.25(1): 122–125 Abstract ( 371 ) PDF (257 KB) ( 428 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2013.01.022

Liquid loading is a common phenomenon during production in tight gas field of Daniudi area, and it seriously affects the normal production of gas wells. Accurate prediction and judgment of the liquid loading of gas wells will provide theoretical basis for dewatering measures. This paper judged the liquid loading of gas wells by using critical slip density method. The result shows that this method can be used to judge the liquid loading of gas wells accurately, and the judgment result is consistent with engineering practice. The method also shows that the gas well will not accumulate liquid immediately except slipping exceeding a certain degree.