Lithologic Reservoirs

Rocks have three volumes and three stresses, so have several compressibility coefficients. Pore compressibility and its applications have been mainly studied in reservoir engineering, and others are seldom touched. This paper focused on the compressibilities of bulk volume and fluid-solid of rocks, and derived their calculation formula. The compressibility of bulk volume of rocks to pore pressure is the same of pore compressibility of rocks. The compressibility of bulk volume of rocks to outer pressure is the function of porosity and skeleton compressibility of rocks. The two-phase compressibility of fluid-solid of rocks is porosity-weighted harmonic mean of fluid compressibility and skeleton compressibility, or porosity-weighted arithmetic mean of reciprocals of fluid compressibility and skeleton compressibility.

Sedimentary sequence and stratigraphic unconformity trap of Jurassic in Sarybulak area, South Turgai Basin

RAN Huaijiang

2015, Vol.27(2): 6–12 Abstract ( 612 ) PDF (1639 KB) ( 400 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.002

The South Turgai Basin in kazakhstan is an important hydrocarbon prospect area, and influenced by the regional structure, the development evolution of Jurassic sedimentary sequence is closely related with tectonic evolution. Because the unexplored favorable structural traps gradually reduced in the study area, the lithostratigraphic reservoirs become an important exploration target. Based on comprehensively analysis of seismic, well logging and core data, through tectonic evolution analysis, establishing sequence stratigraphic framework and sedimentary facies analysis, this paper studied the characteristics of sedimentary sequence and stratigraphic unconformity trap of Jurassic in Sarybulak of A prospect area, South Turgai Basin. The results show that: ①The Jurassic and Cretaceous in the A prospect area experienced three times of large tectonic movements, and formed three second-order sequences. In those second-order sequence stratigraphic frameworks, the target formations of Jurassic can be divided into seven third-order sequences, and each third-order sequence can be subdivided into two to three systems tracts. ②Lacustrine and braided delta sedimentary systems mainly developed in early Jurassic fault depression stage（SQ1 and SQ2）, lacustrine and delta sedimentary systems mainly developed in Middle Jurassic fault-depression transform stage（SQ3 and SQ4）, and lacustrine, delta and fluvial sedimentary systems mainly developed in Late Jurassic depression stage（SQ5，SQ6 and SQ7）. ③The favorable stratigraphic unconformity traps mainly include two types: stratigraphic erosion unconformity traps formed by SQ1, SQ2 and the overlying strata, and stratigraphic onlap unconformity trap formed by SQ5 and the underlying strata.

Evaluation of reservoir sensitivity of Sinian in Gaoshiti-Moxi block, Sichuan Basin

XU Huilin， WANG Xinhai， WEI Shaobo， CHEN Yan， CHEN Peng

2015, Vol.27(2): 13–17 Abstract ( 672 ) PDF (417 KB) ( 334 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.003

Reservoir sensitivity refers to the sensitivity of various factors which may cause damage to reservoir. The main purpose to analysis the reservoir sensitivity is to identify the extent of formation damage caused by sensitive and put forward the preventive measures of the extend of sensitive damage. In order to study the damage factors in the exploitation process in Gaoshiti-Moxi block, this paper carried out a lot of core experimental studies, and used sensitivity experiment evaluation method to evaluate the sensitive degree referring to the reservoir evaluation standard. The results show that the degree of velocity sensitivity is medium to strong, the degree of water sensitivity is weak and the degree of salt sensitivity is medium. When pH value is less than 10, the degree of alkali sensitivity is weak. When pH value is more than 10, the degree of alkali sensitivity is strong. Acidification proved the reservoir permeability of the study area.

Identification of effective source rocks of Lower Cretaceous and its controlling on hydrocarbon accumulation in Chagan Depression

WANG Peng， L IU Guangdi， CAO Zhe， SU Hui， CHANG Junhe

2015, Vol.27(2): 18–25 Abstract ( 560 ) PDF (1414 KB) ( 531 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.004

Identification of effective source rocks is the basis of research on hydrocarbon reservoir-forming in sedimentary basins, and the distribution of effective source rocks has important controls on hydrocarbon accumulation. Based on the characteristics of hydrocarbon generation and expulsion of source rocks, this paper fully considered the control functions of expulsion on hydrocarbon accumulation and analyzed the relations of TOC content with chloroform bitumen “A” and pyrolysis parameter S1. It is considered that the real contributors to hydrocarbon reservoir of Lower Cretaceous are the source rocks whose TOC content is over 1.0%. The logging ΔlogR method was used to predict TOC content in single well. The lowest limit of TOC content was chose as evaluation criteria to determine the thickness and the plane distribution characteristics of effective source rocks in different prospecting wells. The study result shows that effective source rocks mainly distributed in gentle slope belt in Chagan Depression. The thickness of effective source rocks in trough is even thinner. Hydrocarbon reservoirs are mainly enriched in the updip direction of gentle slope belt rather than deep trough. Through the analysis of the superimposition of source-reservoir distribution, oilsource correlation and the match of hydrocarbon generation and accumulation stage, it is believed that hydrocarbon which is generated by effective source rocks in gentle slope belt migrates to trap and forms reservoir through sand bodies and fault. The distribution of effective source rocks in gentle slope belt has significant control on hydrocarbon accumulation in Chagan Depression.

Migration systems and hydrocarbon accumulation models of buried hill reservoirs in Jizhong Depression

GAO Changhai， ZHA Ming， ZHAO Xianzheng， PENG Pu

2015, Vol.27(2): 26–30 Abstract ( 532 ) PDF (1810 KB) ( 477 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.005

The buried hills in Jizhong Depression are abundant in hydrocarbon which is characterized by multi-stage tectonic movements and complex reservoir heterogeneity. The exploration results in recent years indicate that the hydrocarbon migration system in buried hills has become the key factor restricting the exploration. Based on the analysis of structural framework, depositional filling and reservoir characteristics since Mesoproterozoic, it is determined that the hydrocarbon migration pathways of buried hills include fault, unconformity and carbonate reservoir. Among them, faults and unconformities serve as the main migration pathways and control simultaneously the hydrocarbon migration and accumulation with carbonate reservoirs. The assemblage types of hydrocarbon migration system are divided into fault-dominated, unconformity-dominated and fault-unconformity composite according to their functions. On this basis, the hydrocarbon accumulation models can be concluded into three types in combination with differences of zone distribution and structural features, including central uplift belt, fault step belt and ramp belt. The future exploration zones should be focused on the fault step belt and the ramp belt.

Characteristics of pyrite and its hydrocarbon significance of shale reservoir of Doushantuo Formation in middle Yangtze area

X U Zuxin， HAN Shumin，WANG Qichao

2015, Vol.27(2): 31–37 Abstract ( 612 ) PDF (837 KB) ( 717 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.006

Pyrite is a mineral with the deposition of abundant organic matter, and it is not only an important index to restore sedimentary environment, but also can indicate the characteristics of oil and gas in shale reservoirs. This paper used argon-ion polishing-scanning electron microscopy (Ar-SEM) techniques and ImageJ software to study grain size and hydrocarbon significance of shale reservoir of Doushantuo Formation in the Middle Yangtze area. The results show that：①the framboids pyrite in shale of Doushantuo Formation is of small particle size, showing a long anoxic sedimentary environment, which is better for the deposition and preservation of organic matter and provides good conditions for the formation of shale gas; ②the content of pyrite has positive correlation with the content of adsorbed gas in the shale of Doushantuo Formation, thus we can predicate adsorbed gas in shale according to the content of pyrite; ③iron is the necessary material for deposition of organic matter, high iron content is beneficial to the enrichment of organic matter, and the organic matter content influences the shale gas generation and storage capacity, so we can predicate maximum shale gas-bearing area according to the enrichment degree of pyrite.

Study on occurrence features of coalbed methane in Heyang area ， Ordos Basin

Y I Wei， X IONG Xianyue， WANG Wei， L IU Ling

2015, Vol.27(2): 38–45 Abstract ( 691 ) PDF (637 KB) ( 350 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.007

Heyang area in Ordos Basin is an important block of coalbed methane exploration in our country, so to study the occurrence features of coalbed methane and predict coalbed methane resources is necessary for field development. This paper analyzed the occurrence of coalbed methane in this area in respect of coalbed methane reservoir characteristics including burial depth and thickness of coal layer, features of coal, adsorption and pressure of coal reservoirs, permeability of coal reservoirs, as well as gas content. The results show that the preservation conditions of coalbed methane are advantage. The main coal-bearing strata are Shanxi Formation and Taiyuan Formation of the Permian, containing 11 layers coal, of which 4 layers are recoverable or partially recoverable, the cumulative thickness of coal seam is about 11 m, and the main coal seam is NO.5, of which the thickness is more than 3 m. The coals are dominated by lean coal with high ash and low volatile. Less affected by the destruction of tectonic activity, the original structure of coal is more complete, and the gas content of coal reservoir is high and the adsorption is strong. The prediction result of coalbed methane resources in this area shows that coalbed methane mainly occurs in coal layers shallower than 1 600 m with a cumulative coalbed methane resource volume of 442.72× 108 m3. Among them the coalbed methane resource volume with buried depth shallower than 1 300 m is 335.01×108 m3.

Characteristics and main controlling factors of Cenozoic sequence stratigraphy in Wan ’ an Basin, Nansha Islands

WU Dong， ZHU Xiaomin， ZHU Shifa， ZHANG Houhe， ZHAO Dongna， L I Wei

2015, Vol.27(2): 46–54 Abstract ( 702 ) PDF (1772 KB) ( 373 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.008

Wan’an Basin is one of the uppermost basins in the western part of Nansha Islands which develops several significant petroliferous basins. The sedimentary layer mainly consists of conglomerate, sandstone and mudstone of Cenozoic continental facies, marine-continental transitional facies and marine facies. So far, because of the restriction of many factors，the oil and gas exploration progress in Wan’an Basin is slow. A reasonable and reliable sequence stratigraphic framework is necessary and important for analyzing tectonic-sedimentation evolution history and predicting the distribution of sandstone and implementing lithological reservoirs. Based on the drilling, logging and 2D seismic data, under the guidance of sequence stratigraphic theory and method, combined with the tectonicsedimentation evolution background of Cenozoic in South China sea, this paper divided the Cenozoic into three subfirst-order sequences, six second-order sequences and ten third-order sequences （SQ1-SQ10） in Wan’an Basin. SQ1 and SQ2, corresponding to Paleocene-Eocene, can’t be identified completely because of erosion and the limit of seismic quality. The strata of SQ3-SQ10（Oligocene-Quaternary） were developed completely and mainly composed of sand-shale and marine limestone of marine-continental transitional faceis. The controlling factors of sequence stratigraphic development include tectonic movement, sea level change and sediments supply, among which the tectonic movement is the most important factor.

Research progress and new direction ： Catalysis of clay minerals on oil and gas generation

MA Xiangxian， ZHENG Jianjing， WANG Xiaofeng， WANG Zuodong，WU Yingzhong， QIAN Yu

2015, Vol.27(2): 55–61 Abstract ( 639 ) PDF (1630 KB) ( 785 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.009

Clay minerals are main component of hydrocarbon source rocks. They play an important role on oil and gas formation. There are a lot of disputes on present and absent of catalyst for catalytic role, and catalytic behavior performance in what aspects. Most of the researches support that clay minerals have no catalytic effect even have inhibitory effect on hydrocarbon generation In the open water system, but have catalysis in the closed system. There are two views on the catalysis of clay minerals. One view is that the catalysis of clay minerals can improve the hydrocarbon production rate, and increase the kinds of products of hydrocarbon; another think is that the catalysis of clay minerals only changes the composition of the product, without changing the hydrocarbon yield. The catalytic mechanisms of clay minerals are mainly carbon ion mechanism and the mechanism of free radical, which one plays a leading role in geological processes is not clear. The present study mainly focused on catalytic cracking supported by carbon ion mechanism which is lack of research on free radical mechanism, especially the role of free radicals playing in geological process. The research achievements of predecessors in this field were analyzed, to seek the causes of different results, expound new understanding of clay minerals catalytic research and put forward collaborative catalytic systems concept.

Characteristics of basement reservoirs and hydrocarbon accumulation conditions in the northern Kunlun fault zone

LIU Guizhen， ZHANG Deshi， LI Nengwu

2015, Vol.27(2): 62–69 Abstract ( 618 ) PDF (2390 KB) ( 389 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.010

Based on core observation, thin section identification, scanning electron microscopy analysis, logging data and physical properties, this paper studied the characteristics of basement reservoirs and hydrocarbon accumulation conditions in the northern Kunlun fault zone. The results indicate that the basement reservoirs are mainly of granite and metamorphic slate, the reservoir spaces of granite are mainly dissolved fractures, tectonic fractures and dissolved pores, and the main reservoir spaces of slate is tectonic fractures. The main conditions of hydrocarbon accumulation in the basement rocks include good source conditions, rich reservoir spaces of tectonic fractures, dissolved fractures and dissolved pores, as well as various traps and good migration system. Multi-stage faults, unconformity surface and weathering crust are the controlling factors of hydrocarbon accumulation.

Provenance and sedimentary facies evolution of Chang 8 oil reservoir set in Maling area, Ordos Basin

LEI Qihong， GAO Qiongyao， CHENG Liangbing， LI Jihong， YANG Yongxing， GAO Junfeng

2015, Vol.27(2): 70–76 Abstract ( 667 ) PDF (2760 KB) ( 360 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.011

Based on the petrology characteristics, sedimentary structure, biological fossils and grain-size distribution of cores from 15 drilling wells of Chang 8 oil reservoir set in Maling area, combined with heavy and light mineral combination characteristics, variational function of data structure and plane distribution of sand content, this paper analyzed the direction of provenanace and palaeocurrent. The results show that the provenanace and palaeocurrent came from the southwest and northeast of the study area, Chang 8 oil reservoir set developed shallow water front delta facies, and the sedimentary microfacies distribution of each sub-layer changed according to the water flow intensity from the two different directions.

Differences of solvable organic matters with different occurrence states in argillaceous source rocks of coastal shallow-lake facie

YANG Yan， LEI Tianzhu， GUAN Baowen， TIAN Chuntao， WU Yingqin

2015, Vol.27(2): 77–82 Abstract ( 612 ) PDF (421 KB) ( 349 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.012

Through stripping silty mudstone of Cretaceous Zhonggou Formation of in Jiuxi Basin step by step, we obtained solvable organic matters with different occurrence states in argillaceous source rocks of coastal shallow-lake facies, and compared the similarities and differences of geochemical characteristics between them. Three kinds of solvable organic matters were stripped, including organic matters adhered on the surface of the minerals, namely chloroform asphalt “A”, solvable organic matters combined solidly or parceled with carbonate, namely chloroform asphalt “C”, and solvable organic matters integrated with silicate closely, namely the chloroform asphalt “E”, respectively. These three kinds of solvable organic matters were obviously different in terms of quantity and geochemical parameters. The analysis results show that chloroform asphalt “A” had the largest number, next is chloroform asphalt “E”, and chloroform asphalt “C” had the least number. However, both the total hydrocarbon and the saturated hydrocarbons and n-alkanes, the number order from most to least was from the chloroform asphalt “A” to chloroform asphalt “C” to chloroform asphalt “E”. OEP value, Pr/Ph ratio and ∑C22-/∑C22+ value show that the maturity of solvable organic matters was gradually increased from chloroform asphalt “A” to chloroform asphalt “C” to chloroform asphalt “E”. These findings suggest that solvable organic matters always prefer to occupy large pore by physical adsorption, then gradually to the meso-porous and microporous in the process of oil and gas migration; and for similar structures of organic molecules, the smaller the weight of the molecular is, the stronger the activity will be and they will accumulate in meso-porous and microporous relatively, and finally makes the crude oil quality better. Carbonate minerals enriched in non-hydrocarbon compositions easily and the silicate minerals concentrate of the non-hydrocarbon easily and heavy constituents, such as asphaltenes simultaneously.These recognitions above will contribute to fine evaluation of hydrocarbon source rocks and further oil and gas exploration.

Logging evaluation technology and application of tight tuff reservoir in Santanghu Basin

JIAO Lixin， LIU Juntian， LI Liuzhong， HAN Cheng， ZHANG Pin， LONG Fei

2015, Vol.27(2): 83–91 Abstract ( 571 ) PDF (2558 KB) ( 415 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.013

The tuff reservoir of Tiaohu Formation obtained industrial oil flow in many wells in Santanghu Basin, which makes it become a new hot field of exploration in Tuha Oilfield. Research shows that except tuff, the reservoir lithologies include biodetritus, charcoal and a few muddy strips, with some sedimentary characteristics, and the tuff has abundant organic carbon, with large thickness, as good source rocks. The reservoir porosity ranges from 5.5% to 24.0%, the permeability is generally less than 0.5 mD, and the average oil saturation is above 70%, so it belongs to tight tuff reservoir with large pores, ultra-low permeability and high oil saturation. Based on Δlog R logging technology, this paper carried out a quantitative evaluation of hydrocarbon source rocks; on the basis of rock slices and whole-rock mineral analysis, established and improved the identification methods and standards of tuff and mudstone by core logging; combined with core analysis, CT scanning and mercury capillary pressure data, studied microscopic characteristics of the reservoir; conducted effective reservoir evaluation and porosity calculation by combined logging data; on the basis of the reservoir lithology, carried out oil-bearing property evaluation, basically formed a set of techniques and methods of logging evaluation for tight tuff reservoir, and achieved good effects in production.

Suppressing scheme of multi-frequency component industrial interference and its application

CHEN Keyang

2015, Vol.27(2): 92–97 Abstract ( 470 ) PDF (3951 KB) ( 332 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.014

In order to solve the problems of the low calculating efficiency and low processing precision of the current industrial interference suppression process in industrial software, this paper presented and derived a new scheme to suppress multi-frequency component industrial interferences simultaneously. The algorithm uses a combination of cosine functions to approximate the industrial interference, and achieves automatic identification and adaptive suppression of multi-frequency component industrial interference according to the optimal approximation of least square method and the normalized cross-correlation coefficient. It was applied to theoretical synthetic model and practical seismic data in CD area of Songliao Basin. the result shows that the proposed scheme is with perfect amplitude preserved and high signal to noise ratio, therefore, the new algorithm can be an important technical guidance for high precision amplitude preserved seismic data preprocessing in mature exploration area.

Interference well test with numerical simulation design and program optimization at sea

YAN Zhenghe， GUO Kangliang， LI Yanping， CHENG Chuchuan， YANG Yong， LIU Yuanzhi

2015, Vol.27(2): 98–102 Abstract ( 681 ) PDF (908 KB) ( 360 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.015

The reservoir of an oilfield located in the eastern South China Sea is characterized by good reservoir permeability, different water content in each well and serious interference between production wells. Aiming at this phenomenon, based on seepage flow mechanics and existing geological data, this paper carried out interference well test numerical simulation and designed construction program to ascertain interwell connectivity and find out interference pressure. Compared with conventional methods, interference well test numerical simulation can realize the combination of fine grid blocks in near bore zones and coarse grid blocks in far bore zones, and then achieved the purpose of describing geological characteristics with least grid blocks and simulated oil and water seepage of multiphase flow at the same time, which has favorable guidance for practical construction tests. The actual interference pressure date collected from optimized interference well test construction matched with the initial designing project, which validates the correctness of this design scheme.

Estimation of water influx in condensate gas pool by means of productivity index curve

CHEN Jun， QIN Ke， REN Hongwei， YIN Shuangjiang， LI Bing

2015, Vol.27(2): 103–108 Abstract ( 609 ) PDF (347 KB) ( 469 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.016

Water drive condensate gas reservoir account for a certain proportion in developed gas field. There is a special phenomenon that this type of gas reservoir could condensate in the progress of development, resulting more complicated calculation of the water influx. As a special gas reservoir for condensate gas reservoir, the retrograde condensation liquid will appear in the fluid when the pressure is below dew point pressure. Based on the production characteristics of condensate gas reservoir, this paper derived a new linear material balance equation of water drive condensate gas reservoir, and it takes the influence of condensate oil on the calculation of water influx in gas reservoir into account when the pressure is below dew point pressure. Production index curve drawn by means of this equation can be used to calculate the water index of condensate gas reservoir in different periods conveniently, fast and accurately. Example application shows that compared with the rest calculation methods, this method is simpler and faster and the calculated result is more accurate and practical.

Calculation model of breakdown pressure in shale formation

YAN Xiangyang,HU Yongquan,LINan,SHEN Beibei

2015, Vol.27(2): 109–113 Abstract ( 650 ) PDF (305 KB) ( 459 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.017

It is very important to predict formation fracture pressure accurately for successful hydraulic fracturing. Calculating the fracture pressure in shale formation is different from that in common formations as a result of changes of mechanical properties due to hydration, so the calculation method of common formations cannot be applied to mud shale formation and an in-depth research should be made on the calculation method of fracture pressure in shale formation. Therefore, based on theories of elastic mechanics and rock mechanics, considering the effect of hydration on the wellbore stress field, this paper applied maximum tensile stress criterion to establish a new model for calculating fracture pressure by taking hydration stress into account. Besides, this paper carried out calculation examples by using the established model combined with two ways to calculate hydration stress of shale. The result shows that the fracture pressure in shale formation with hydration stress considered is much closer to the fracture pressure in actual formation than that not considered. Hence, this calculation model provides a reference basis for fast predicting the formation fracture pressure.

Optimization of development of highly deviated well in gas reservoir with bottom water

ZHANG Yu， ZHONG Haiquan， LI Yongchen， GUO Chunqiu， SHI Haidong

2015, Vol.27(2): 114–118 Abstract ( 571 ) PDF (344 KB) ( 337 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.018

The most important matter on the development of highly deviated well in gas reservoir with bottom water is water coning. A basic model of highly deviated well in gas reservoir with bottom water was established by means of numerical simulation methods. Applying orthogonal design method to analyze the interaction of compound parameters during highly deviated well developing the gas reservoir with bottom water can quickly and accurately obtain a more reasonable holistic optimization result different from the conventional local optimization with single parameter. Meanwhile, for the sake of accurate simulating of development features, used multi-segment well model to consider the effect of the friction and flow coupling between formation and well bore, and applied tracers to accurately simulate water breakthrough time of bottom water, which make the index optimization more reasonable and reliable. The result shows that the height of water avoidance at the toe of deviated segment can affect water breakthrough time and water-free recovery percent obviously, and the length of deviated segment and producing pressure drop play a major role on the recovery percent in the final prediction.This study has importance in guiding efficient development of highly deviated well in gas reservoir with bottomwater.

A new method to study the productivity of horizontal gas well after acidizing

YUAN Lin， LI Xiaoping， YAN Yichen， WANG Xiaolei， CHENG Ziyang

2015, Vol.27(2): 119–125 Abstract ( 445 ) PDF (837 KB) ( 353 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.019

The technology of horizontal well acidizing had been widely used in developing the gas field, but because of the particularity of flow pattern of horizontal well and damage mode near the wellbore, the fluid seepage in formation will become more and more complex after acidizing, so the study on productivity after acidizing will be of great importance. Based on the non-uniform distribution of damage zone and acidizing zone near the horizontal wellbore, this paper divided the composition area near the wellbore into several homogeneous regions, used the method of displacement between two similar flow modes to get a new method to calculate the skin factor of horizontal well after acidizing, considered the pressure drop in the wellbore, and coupled the wellbore conduit flow and formation seepage. Case study shows that the productivity of horizontal well was greatly increased after acidizing, meanwhile, as the increasing of gas reservoir thickness, permeability of acidizing zone and the distance of acid-rock reaction, the production-increasing ratio also increases, but as the increasing of permeability of damage zone and distance of mud immersion, the productionincreasing ratio decreases.

Research on well interference of coalbed methane wells and its application

YAN Xia， LI Xiaojun， ZHAO Hui， ZHANG Wei， WANG Zebin， MAO Delei

2015, Vol.27(2): 126–132 Abstract ( 565 ) PDF (694 KB) ( 829 )

doi: https://doi.org/10.3969/j.issn.1673-8926.2015.02.020

Well interference of coalbed methane wells is a kind of effective technologies to achieve high and stable gas production rate. At present, there are many studies on the interference phenomenon of coalbed methane wells, but less quantification work of wells interference in the field. According to the drainage features of coalbed methane wells, this paper proposed a new convenient, reliable and efficient method to determine and quantify the wells interference phenomenon, which is on the basis of the difference between observed start-pumping water level and original water level of coal bed methane wells. During the drainage process, the interference phenomenon of coal bed methane wells can be quantified more precisely by the new method. By comparing the results of the proposed method and theory method in the real case in Baode block, the reliability of the proposed method was verified. By the new method, the quantified characteristics and rules of interfered coal bed methane wells in Baode Block were summarized. Hence some reasonable application suggestions of interference of coalbed methane wells were provided, such as proper arrangement of well placement, increase of gas production rate, shortage of gas breakthrough period and optimization of production system.