en
×

分享给微信好友或者朋友圈

使用微信“扫一扫”功能。
作者简介:

李站伟(1993—),男,河南周口人,在读硕士研究生,从事非常规地质理论与评价方面的研究工作。E-mail:lizw1718@163.com。

通讯作者:

陈世达(1991—),男,山东日照人,讲师,博士。E-mail:Shida.Chen@cugb.edu.cn。

中图分类号:TE132.2

文献标识码:A

文章编号:1009-9603(2021)01-0125-07

DOI:10.13673/j.cnki.cn37-1359/te.2021.01.015

参考文献 1
QIN Y,MOORE T A,SHEN J,et al.Resources and geology of coalbed methane in China:a review[J].International Geology Review,2018,60(5/6):777-812.
参考文献 2
徐宏杰,桑树勋,杨景芬,等.贵州省煤层气勘探开发现状与展望[J].煤炭科学技术,2016,44(2):1-7,196.XU Hongjie,SANG Shuxun,YANG Jingfen,et al.Status and expectation on coalbed methane exploration and development in Guizhou Province[J].Coal Science and Technology,2016,44(2):1-7,196.
参考文献 3
国土资源部油气资源战略研究中心.全国煤层气资源评价 [M].北京:中国大地出版社,2009.Strategic Research Center of Oil and Gas Resources,Ministry of Land and Resources.Assessment of coalbed methane[M].Beijing:China Land Press,2009.
参考文献 4
高弟,秦勇,易同生.论贵州煤层气地质特点与勘探开发战略 [J].中国煤炭地质,2009,21(3):20-23.GAO Di,QIN Yong,YI Tongsheng.Geological condition,exploration and exploitation strategy of coal-bed methane resources in Guizhou,China[J].Coal Geology of China,2009,21(3):20-23.
参考文献 5
秦勇,熊孟辉,易同生,等.论多层叠置独立含煤层气系统—— 以贵州织金—纳雍煤田水公河向斜为例[J].地质论评,2008,54(1):65-70.QIN Yong,XIONG Menghui,YI Tongsheng,et al.On unattached multiple superposed coalbed-methane system:in a case of the Shuigonghe syncline,Zhijin-Nayong coalfield,Guizhou[J].Geology Review,2008,54(1):65-70.
参考文献 6
秦勇,申建,沈玉林.叠置含气系统共采兼容性:煤系“三气”及深部煤层气开采中的共性地质问题[J].煤炭学报,2016,41(1):14-23.QIN Yong,SHEN Jian,SHEN Yulin.Joint mining compatibility of superposed gas-bearing systems:A general geological problem for extraction of three natural gases and deep CBM in coal series [J].Journal of China Coal Society,2016,41(1):14-23.
参考文献 7
吴财芳,刘小磊,张莎莎.滇东黔西多煤层地区煤层气“层次递阶”地质选区指标体系构建[J].煤炭学报,2018,43(6):1 647-1 653.WU Caifang,LIU Xiaolei,ZHANG Shasha.Construction of index system of“Hierarchical progressive”geological selection of coalbed methane in multiple seam area of eastern Yunnan and western Guizhou[J].Journal of China Coal Society,2018,43(6):1 647-1 653.
参考文献 8
杨兆彪,张争光,秦勇,等.多煤层条件下煤层气开发产层组合优化方法[J].石油勘探与开发,2018,45(2):297-304.YANG Zhaobiao,ZHANG Zhengguang,QIN Yong,et al.Optimization methods of production layer combination for coalbed methane development in multi-coal seams[J].Petroleum Exploration and Development,2018,45(2):297-304.
参考文献 9
秦勇,吴建光,申建,等.煤系气合采地质技术前缘性探索[J].煤炭学报,2018,43(6):1 504-1 516.QIN Yong,WU Jianguang,SHEN Jian,et al.Frontier research of geological technology for coal measure gas joint-mining[J].Journal of China Coal Society,2018,43(6):1 504-1 516.
参考文献 10
周效志,桑树勋,易同生,等.煤层气合层开发上部产层暴露的伤害机理[J].天然气工业,2016,36(6):52-59.ZHOU Xiaozhi,SANG Shuxun,YI Tongsheng,et al.Damage mechanism of upper exposed producing layers during CBM multi-coal seam development[J].Natural Gas Industry,2016,36(6):52-59.
参考文献 11
张政,秦勇,WANG Guoxiong,等.基于等温吸附实验的煤层气解吸阶段数值描述[J].中国科学:地球科学,2013,43(8):1 352-1 358.ZHANG Zheng,QIN Yong,WANG Guoxiong,et al.Numerical description of coalbed methane desorption stages based on isothermal adsorption experiment[J].Scientia Sinica:Terrae,2013,43(8):1 352-1 358.
参考文献 12
孟艳军,汤达祯,许浩,等.煤层气解吸阶段划分方法及其意义 [J].石油勘探与开发,2014,41(5):612-617.MENG Yanjun,TANG Dazhen,XU Hao,et al.Division of coalbed methane desorption stages and its significance[J].Petroleum Exploration and Development,2014,41(5):612-617.
参考文献 13
康永尚,王金,姜杉钰,等.量化指标在煤层气开发潜力定量评价中的应用[J].石油学报,2017,38(6):677-686.KANG Yongshang,WANG Jin,JIANG Shanyu,et al.Application of quantitative indexes in quantitative evaluation of coalbed methane development potential[J].Acta Petrolei Sinica,2017,38(6):677-686.
参考文献 14
秦勇,郑长东,王博洋,等.基于等温吸附曲线的煤储层产气潜力定量评价——以黔北地区长岗矿区为例[J].天然气工业,2018,38(9):40-47.QIN Yong,ZHENG Changdong,WANG Boyang,et al.Quantitative evaluation on the gas production potential of coal reservoirs based on isothermal adsorption curves:A case study of the Changgang Field,northern Guizhou,China[J].Natural Gas Industry,2018,38(9):40-47.
参考文献 15
LANGMUIR I.The constitution and fundamental properties of solids and liquids[J].Journal of the American Chemical Society,1916,38(11):1 553-1 564.
参考文献 16
易同生,高为.六盘水煤田上二叠统煤系气成藏特征及共探共采方向[J].煤炭学报,2018,43(6):1 553-1 564.YI Tongsheng,GAO Wei.Reservoir formation characteristics as well as co-exploration and co-mining orientation of Upper Permian coal-bearing gas in Liupanshui Coalfield[J].Journal of China Coal Society,2018,43(6):1 553-1 564.
参考文献 17
THOMMES M,CYCHOSZ K A.Physical adsorption characterization of nanoporous materials:progress and challenges[J].Adsorption,2014,2(2/3):233-250.
参考文献 18
周军平,鲜学福,姜永东,等.考虑有效应力和煤基质收缩效应的渗透率模型[J].西南石油大学学报:自然科学版,2009,31(1):4-8.ZHOU Junping,XIAN Xuefu,JIANG Yongdong,et al.A permeability model considering the effective stress and coal matrix shrinking effect[J].Journal of Southwest Petroleum University:Science & Technology Edition,2009,31(1):4-8.
参考文献 19
张先敏,同登科,孙宝全.考虑基质收缩效应的致密煤储层数值模拟[J].应用基础与工程科学学报,2009,17(5):690-696.ZHANG Xianmin,TONG Dengke,SUN Baoquan.Numerical simulation of tight coalbed methane reservoir with the matrix shrinkage effect[J].Journal of Basic Science and Engineering,2009,17(5):690-696.
参考文献 20
秦勇.叠置含气系统煤层气开发地质单元与开发方式[R].成都:国家科技重大专项课题年度报告会,2018.QIN Yong.Development methods and development geological unit for superposed CBM-bearing system[R].Chengdu:Annual Report of National Science and Technology Major Projects,2018.
参考文献 21
胡海洋,赵凌云,陈捷,等.基于煤储层可采性的多煤层合采开发层段优选——以黔西地区发耳矿区为例[J].断块油气田,2019,26(6):775-779.HU Haiyang,ZHAO Lingyun,CHEN Jie,et al.Optimum selection of multi-seam development based on coal reservoir mineability:a case study of western Guizhou Fa’er ming area[J].Fault-Block Oil and Gas Field,2019,26(6):775-779.
参考文献 22
胡海洋,赵凌云,金军,等.黔西煤层应力敏感性及对煤层气井排采的影响[J].断块油气田,2019,26(4):475-479.HU Haiyang,ZHAO Lingyun,JIN Jun,et al.Stress sensitivity of western Guizhou coal reservoir and its influence on drainage of CBM well[J].Fault-Block Oil and Gas Field,2019,26(4):475-479.
参考文献 23
李陈,赵刚,陈丽群.考虑基质收缩效应的煤层气藏产能评价 [J].特种油气藏,2019,26(1):106-110.LI Chen,ZHAO Gang,CHEN Liqun.Productivity evaluation of coalbed methane reservoir with matrix shrinkage effect[J].Special Oil & Gas Reservoirs,2019,26(1):106-110.
参考文献 24
闫霞,温声明,聂志宏,等.影响煤层气开发效果的地质因素再认识[J].断块油气田,2020,27(3):375-380.YAN Xia,WEN Shengming,NIE Zhihong,et al.Re-recognition of geological factors affecting coalbed methane development effect [J].Fault-Block Oil and Gas Field,2020,27(3):375-380.
参考文献 25
王镜惠,王美冬,田锋,等.高煤阶煤层气储层产气能力定量评价[J].油气地质与采收率,2019,26(4):105-110.WANG Jinghui,WANG Meidong,TIAN Feng,et al.Quantitative evaluation of production capacity of high rank coalbed methane reservoir[J].Petroleum Geology and Recovery Efficiency,2019,26(4):105-110.
参考文献 26
郭晨,卢玲玲.黔西煤层气成藏特性空间分异及其对开发的启示[J].煤炭学报,2016,41(8):2 006-2 016.GUO Chen,LU Lingling.Spatial distribution and variation of coalbed methane reservoir characteristics and its significance for CBM development in Western Guizhou[J].Journal of China Coal Society,2016,41(8):2 006-2 016.
参考文献 27
曾毅.限流压裂工艺在织金煤层气开发中的应用[J].油气藏评价与开发,2014,4(3):73-77.ZENG Yi.Application of limited entry fracturing technology in CBM development of Zhijin area[J].Reservoir Evaluation and Development,2014,4(3):73-77.
目录contents

    摘要

    为研究黔西-滇东地区煤岩变质程度控制下的煤岩吸附-解吸特征,基于83块煤岩样品的甲烷等温吸附曲线系统分析,建立煤岩吸附-解吸特征参数与煤岩变质程度之间的数学统计模型,并探讨其对多煤层合采产层组合优化的指示意义。研究结果表明:随着煤级的增高,煤岩趋于致密化,微小孔的比表面积大幅增加,对甲烷的吸附能力也显著增强;解吸关键压力节点(启动压力、转折压力、敏感压力)及各解吸阶段(低效解吸阶段、缓慢解吸阶段、快速解吸阶段、敏感解吸阶段)覆盖压差也随之增大。当镜质组反射率大于3.0%时,煤岩储渗空间及吸附-解吸特征参数开始趋于稳定。研究区煤岩变质程度的差异分布和叠置压力系统的空间分异,进一步导致不同煤层解吸产气过程的复杂化。从多层合采的角度而言,在煤层暴露之前,确保产层实现较高的解吸效率,才能保证合采产能和分层贡献,并据此划分出产层组合评价的七类约束条件,进而用于指导多层合采方案的设计。

    Abstract

    CH4 isothermal adsorption curves of 83 coal samples were systematically analyzed,and the statistical model between coal rank and parameters related to adsorption-desorption characteristics were established to reveal the influence of coal rank on CBM adsorption-desorption characteristics in the western Guizhou-eastern Yunnan region. Also,its implications on the optimization of production-layer combination were discussed. The analysis shows that a higher coal rank leads to denser coal,much larger specific surface areas of micropores,and further better adsorption to CH4,resulting in higher desorption pressure at key nodes(starting,turning,and sensitive points)and greater overburden pressure differences at every desorption stage(inefficient,slow,fast,and sensitive stages). When vitrinite reflectance is more than 3.0%,the pore-fracture system and CBM adsorption-desorption characteristic parameters of coal tend to be stable. This differential distribution of coal rank in the study area and the spatial differentiation of the superimposed pressure system further complicate the desorption of different coalbeds. The high desorption efficiency of each production layer before coalbed exposure is an im-portant prerequisite to ensuring the commingled production and gas productivity of each layer. Based on this,the seven constraints on the feasibility of the production-layer combination are identified to guide the future project design of commingled production.

  • 多煤层地区煤层气累积资源量大,但单层资源丰度较低[1-3]。现行技术条件下,多煤层共采是实现煤层气资源高效开发的必要手段之一[4]。黔西-滇东地区已实现单井和少数区块产气突破,但在多煤层条件下,储层空间展布形态多变,煤体结构复杂,加之含气系统垂向叠置,致使横向甜点区优选及纵向产层组合设计难度增加[25]。合采产能动态受煤储层之间的物性差异控制[6],以中国矿业大学为主的研究团队提出了一系列合采产层组合优化设计方法,为西南地区煤层气产层组合设计和工程部署提供了重要的理论支撑[7-9]。然而,煤层气合采产层组合还需综合考虑煤产层的储层压力、解吸过程与动液面动态变化的关系[9-10]。目前,合采选层方法多是基于“动液面降至煤层(或煤层暴露)之前能否实现解吸”这一问题进行探讨,忽略了煤层气的解吸效率和产气能力问题。假设在煤层气的吸附与解吸完全可逆的前提下,可以通过甲烷等温吸附曲线对其解吸过程进行定量表征[11-15]

  • 黔西-滇东地区是多煤层发育的典型地区,其煤层数量多,但单层厚度薄,且煤层厚度平面分布不均一。在深成变质作用的基础上,部分地区还叠加了岩浆热变质作用和热液变质作用,导致煤级分布极为广泛,自气煤至无烟煤均有发育,直接或间接地控制着区域煤储层的生烃潜力和储集能力。本次研究针对黔西-滇东地区多煤层的煤层气开发实际,基于六盘水、织纳、水城、格目底和恩洪-老厂等矿区的83块煤岩样品的甲烷等温吸附曲线,借鉴煤层气解吸阶段划分方法,通过回归分析,建立煤岩变质程度与吸附-解吸特征参数之间的数学统计模型,进而探讨甲烷解吸产气过程对煤层开发的指示意义,以期为研究区煤层气的高效开发提供指导。

  • 1 不同变质程度煤岩吸附特征

  • 黔西-滇东地区煤岩的兰氏体积(VL)和兰氏压力(pL)分布范围较广,分别为 2.61~39.53 m3/t 和 0.35~2.86 MPa(图1)。煤岩的热演化程度对甲烷吸附能力的影响较为显著,VLpL均随着煤阶的增高而显著增大,这种上升趋势在镜质组反射率(Ro)小于 3% 时最为明显;当 Ro值大于 3% 时,煤岩吸附特征参数的变化幅度有所降低并逐渐趋于平稳,这与前人研究结果基本一致[16]。其中,VLpLRo值的关系可以表示为:

  • VL=-2.7801Ro2+24.817Ro-17.804
    (1)
  • pL=-0.1379Ro2+1.3544Ro-0.564
    (2)
  • 图1 黔西-滇东地区煤岩镜质组反射率与兰氏体积、兰氏压力之间的关系

  • Fig.1 Correlations of vitrinite reflectance with Langmuir volume and Langmuir pressure of coal in the western Guizhou-eastern Yunan region

  • 煤岩的甲烷等温吸附曲线形态随着煤阶的增高也表现出较为明显的差异。当 Ro值小于 3% 时,在相同压力条件下,较高变质程度煤岩的甲烷吸附量始终高于较低变质程度煤岩。随着煤岩变质程度的进一步增高,即Ro值大于3%时,甲烷等温吸附曲线在低压区基本重合,只有当压力大于5 MPa时,甲烷等温吸附曲线形态差异才开始趋于明显。

  • 煤岩变质程度对甲烷吸附能力的影响受控于煤岩储渗空间的演化[17]。进一步对黔西-滇东地区 10块煤岩样品开展低场核磁共振实验发现,随着煤岩变质程度的增高,煤岩整体趋于致密化,核磁共振 T2谱的谱峰逐渐向左偏移,反映出煤岩渗流空间的显著减少和吸附空间的大幅增多(图2)。

  • 低温N2(测试孔径为2~100 nm)和CO2(测试孔径为0.5~1 nm)吸附实验可以通过对煤岩比表面积进行量化表征,反映煤岩吸附空间的变化。由黔西六盘水矿区盘关向斜 14 块煤岩样品的 Ro值与比表面积的关系(图3)可见,随着煤岩变质程度的增高,煤岩比表面积显著增大,但增幅逐渐趋于平缓,与煤岩吸附特征参数随 Ro值的变化趋势高度一致。综合核磁共振实验结果认为,高变质程度煤岩的大孔及微裂隙相对不发育,以微小孔为主,煤岩基质比表面积较大,可以为甲烷提供更多的有效吸附空间,因此兰氏体积也随之增大。

  • 图2 黔西-滇东地区不同变质程度煤岩核磁共振 T2谱曲线特征

  • Fig.2 The T2 spectra of different coal ranks in western Guizhou-eastern Yunan region

  • 2 不同变质程度煤岩解吸特征

  • 张政等基于兰格缪尔等温吸附方程和数学曲率方程,以启动压力、转折压力和敏感压力为节点,划分了煤层气低效解吸阶段、缓慢解吸阶段、快速解吸阶段和敏感解吸阶段[11-12]。启动压力、转折压力和敏感压力的计算公式分别为:

  • 图3 黔西六盘水矿区盘关向斜煤岩样品Ro值与比表面积的关系

  • Fig.3 Correlation between vitrinite reflectance and specific surface area of coal samples from Panguan syncline in Liupanshui mining area,western Guizhou

  • pi=7+41414×VLpL-pL
    (3)
  • pt=VLpL-pL
    (4)
  • ps=7-41414×VLpL-pL
    (5)
  • 快速和敏感解吸阶段所对应的煤层气解吸效率较高,对煤产层的产气能力和生产井的最终产能具有重要影响。

  • 根据(3)式—(5)式,计算得到黔西-滇东地区 83 块煤岩样品的启动压力、转折压力和敏感压力,并分别建立其与 Ro值的相关关系。结果(图4)表明,煤岩样品的启动压力、转折压力和敏感压力均随着 Ro值的增加而增大,其变化趋势与兰氏体积的变化趋势基本相似;即在初始饱和吸附条件下,高变质程度煤岩相对于低变质程度煤岩更容易实现高煤层气解吸效率。此外,随着煤岩变质程度的增高,相邻解吸压力节点的差值(覆盖压差)也逐渐增大,说明高变质程度煤岩跨越某一个解吸阶段相对于低变质程度煤岩所需要的理论压降更大、时间更长,生产上可能会表现为某一阶段产气量的相对缓慢上升。研究区煤岩样品的关键解吸压力节点与 Ro值的拟合关系为:

  • pi=-0.6952Ro2+6.497Ro-4.135
    (6)
  • pt=-0.5132Ro2+4.628Ro-3.086
    (7)
  • 图4 黔西-滇东地区煤岩解吸压力节点与煤岩变质程度的关系

  • Fig.4 Correlation of desorption-pressure nodes and coal rank in western guizhou-eastern Yunnan region

  • ps=-0.2688Ro2+2.371Ro-1.706
    (8)
  • 煤层气解吸阶段划分是在初始饱和吸附条件下进行的,而对实际煤层气藏(特别是欠饱和煤层气藏)评价时,还需考虑煤层的含气性。对于多数煤层气藏,在地质历史过程中部分煤层气已经发生解吸逸散,因此在实际开发过程中绝大多数煤层仅经历部分煤层气解吸阶段。通常煤层气开发早期较高的解吸效率对形成高产气井至关重要,因此,煤层气井临界解吸压力下的解吸效率能够反映气井早期的产气特征。临界解吸压力是气体开始从煤岩基质表面解吸时所对应的储层压力,可以由含气量、兰氏体积和兰氏压力计算[17]

  • pcd=VpLVL-V
    (9)
  • 将(1)式和(2)式代入(9)式,则研究区煤层气的临界解吸压力可以近似表示为:

  • pcd=V-0.138Ro2+1.354Ro-0.564-2.78Ro2+24.82Ro-17.8-V
    (10)
  • 基于(6)式—(8)式和(10)式,可以得到不同变质程度煤岩临界解吸压力随实测含气量变化及其与不同解吸压力节点关系的理论图版(图5)。煤岩解吸初期对应的高解吸效率一方面有利于煤层气的快速产出,另一方面也可以增强基质收缩效应,是实现气井高产的有利条件[18-19]。当然,如果煤层气藏含气量或含气饱和度较低,即便其理论解吸效率较高,也难以达到理想产能。

  • 3 对多煤层合采产层组合优化的指示意义

  • 黔西-滇东地区叠置含气系统的存在使得煤储层压力和含气量在垂向上存在波动变化,这必然导致同一井筒内不同煤层解吸特征和产气过程的复杂性。基于织金区块探井和小井组的成功试验,并借鉴秦勇等提出的“三压一动逐层约束法”[920],笔者提取动液面高度、解吸压力节点、储层压力和煤层间距等参数,从煤层气解吸角度建立产层组合兼容性评价方法。以 2 套煤组合为例,假设上部煤层距初始静液面高度为∆H;上、下部煤层的间距为 h; 上部煤层的储层压力、临界解吸压力、转折压力和敏感压力分别为 p1pcd1pt1ps1;下部煤层的储层压力、临界解吸压力、转折压力和敏感压力分别为 p2pcd2pt2ps2

  • 图5 不同变质程度煤岩临界解吸压力随实测含气量变化及其与不同解吸压力节点的关系

  • Fig.5 Variation of critical desorption pressure with measured gas content of different coal ranks and its relationship with desorption pressure nodes

  • 临储压差定义为煤储层的储层压力与临界解吸压力的差值,则上、下部煤层的临储压差分别为:

  • p临储 1=p1-pcd1p临储2 =p2-pcd2
    (11)
  • 转储压差定义为煤储层的储层压力与转折压力的差值,则上、下部煤层的转储压差分别为:

  • p转储 1=p1-pt1p转储 2=p2-pt2
    (12)
  • 敏储压差定义为煤储层的储层压力与敏感压力的差值,则上、下部煤层的敏储压差分别为:

  • p敏储 1=p1-ps1p敏储 2=p2-ps2
    (13)
  • 动液面降低至上部煤层顶板时,近井地带储层压力降幅可以表示为:

  • pd=ρgΔH0.98ΔH
    (14)
  • 对多层合采煤层气井而言,随着开发的进行,井筒内动液面将逐渐降低至各产层以下。若动液面过早地降低至煤层以下,则可能对储层造成伤害。然而,目前关于动液面降低对产能的伤害机理尚未达成共识,特别是对其在生产上的具体显现特征缺乏定量的表征。周效志等认为动液面降低至上部产层以下后,近井地带的地层水、压裂液将难以排出,进而导致上部产层的产水量和产气量快速下降[10]。从这一点来看,在动液面降低至煤层以下之前比之后更容易实现压降的传播和解吸面积的扩大。在产层暴露前实现较高的解吸效率,可以增大解吸体积,增强基质收缩效应,对提高渗透率和气井产能具有促进作用。因此,笔者以上部煤层与动液面的关系为基准,将一个产层组合中各煤层的解吸进程和动液面高度的动态变化划分为七类约束条件,进而评价不同产层组合条件下的合采可行性(表1)。

  • 表1 合采产层解吸进程与动液面高度的动态变化关系

  • Table1 Correlation between desorption process and dynamic fluid level of commingled production layers

  • 表 1的产能评价中自 A到 G代表合采井的产能或产气潜力逐渐降低,其中以A为最佳,G代表合采井不能产气。当约束条件满足类别Ⅲ—Ⅶ时,可以进行产层组合,但是不同产层组合的产气能力和产气贡献有所不同。类别Ⅲ仅能保证所有煤层可以实现解吸,无法保证产气能力。相比之下,类别Ⅶ 在动液面降至上部煤层之前,所有产层均可进入敏感解吸阶段,并达到较高的解吸效率,多煤层共同快速产气形成合力,是多层合采的最佳组合方案。

  • 对于初始阶段即处于快速和敏感解吸阶段的煤层,即满足类别Ⅴ—Ⅶ的约束条件下,煤层解吸后动液面距上部煤层顶部仍有一定距离时,可以保证上部煤层压降漏斗扩展和累积产气量的最大化。以珠藏向斜 Z4井为例,该井选层跨度达 240 m,分 3段对Ⅰ煤组 5#和 6#煤层,Ⅱ煤组 16#煤层,Ⅲ煤组 20#,23#,27#和30#煤层进行多层合采。开采初期,初始液面为 1.88 m,井底流压为 3 MPa。排采46d后,Ⅰ煤组的 2 套煤层解吸动液面为 170 m;由于高解吸效率,产气量迅速上升至约为1000m3 /d;但随即暴露,压降漏斗未能得到充分的扩展;后续供气面积有限,产气量迅速衰减。后期Ⅲ煤组煤层解吸后,产气量又开始急速回升,此时液柱距Ⅲ煤组仍有较大的可压降空间,从而保证了产气高峰的不断后移(或稳定产气)。尽管Z4井实现了高产,但Ⅰ和 Ⅱ煤组的产气量贡献有限。后续小井组的 10 口煤层气井以Ⅲ煤组 20#,23#,27#和 30#煤层为目标层位进行合采,各产层敏感解吸阶段后平均可降液柱高度为 256 m,平均排采时间为 400d,单井峰值产气量大于2000m3 /d,稳定产气量超过1300m3 /d,实现了黔西地区煤层气多层合采的新突破(图6)。

  • 图6 珠藏向斜Z4井排采曲线特征

  • Fig.6 Production curve of Well Z4 in Zhuzang syncline

  • 值得注意的是,多层合采井的效益开发是合理的地质选层、有效的工程施工以及后期科学的排采管理综合作用的结果。解吸进程与动液面的动态关系可作为产层组合的约束条件之一,而合理的层位组合需考虑埋深、煤体结构、含气性、煤层间距、渗透性、储层压力及水文地质条件等多种因素[7-921-25]。从渗透性的角度而言,黔西-滇东地区煤层原位渗透率较低(试井渗透率普遍小于 0.5 mD[26]),后期的渗流能力很大程度上取决于水力压裂改造效果。从织金区块的开发实践来看,碎裂煤具备良好的可改造能力及产气潜力,而碎粒/糜棱煤的压裂改造效果受限,易导致气井低产。从压裂模式来看,以单层为改造单元的分层压裂方式的储层改造针对性强,可以确保各产层充分改造,保证其产能贡献,而多层合压开采则难以全面兼顾,部分煤层可能并未得到有效改造,产气效果整体不佳[27]。从解吸的角度来讲,如果一个组合段中各煤层的解吸进程不均一(例如存在低解吸效率层位),可采取差异化的压裂方式和压裂规模,对某些层位进行针对性的改造,以提高其产能贡献。

  • 4 结论

  • 煤岩变质程度是影响黔西-滇东地区储层吸附能力的重要因素。随着镜质组反射率的增加,煤岩趋于致密,微小孔逐渐占主导地位,对甲烷的吸附能力显著提升,兰氏体积也随之增大。借鉴煤层气解吸阶段划分方法,建立了研究区煤岩变质程度与关键解吸压力节点之间的数学统计模型,得到了不同变质程度煤岩临界解吸压力随实测含气量变化及其与不同解吸压力节点的关系。通过提取动液面高度、解吸压力节点、储层压力和煤层间距等参数,从煤层解吸的角度划分了七类约束条件作为产层组合评价的指标,以提高地质选层的成功率。

  • 符号解释

  • g——重力加速度,m/s2

  • h——上、下部煤层的间距,m;

  • H——上部煤层距初始静液面高度,m;

  • p1——上部煤层的储层压力,MPa;

  • p2——下部煤层的储层压力,MPa;

  • pcd——临界解吸压力,MPa;

  • pcd1——上部煤层的临界解吸压力,MPa;

  • pcd2——下部煤层的临界解吸压力,MPa;

  • pd——近井地带储层压力降幅,MPa;

  • pi ——启动压力,MPa;

  • pL——兰氏压力,MPa;

  • ps——敏感压力,MPa;

  • ps1——上部煤层的敏感压力,MPa;

  • ps2——下部煤层的敏感压力,MPa;

  • pt ——转折压力,MPa;

  • pt1——上部煤层的转折压力,MPa;

  • pt2——下部煤层的转折压力,MPa

  • p临储1——上部煤层的临储压差,MPa;

  • p临储2——下部煤层的临储压差,MPa;

  • p转储1——上部煤层的转储压差,MPa;

  • p转储2——下部煤层的转储压差,MPa;

  • p敏储1——上部煤层的敏储压差,MPa;

  • p敏储2——下部煤层的敏储压差,MPa;

  • Ro——镜质组反射率,%;

  • VL——兰氏体积,m3 /t;

  • V——含气量,m3 /t;

  • x——常数,取值为 1 或 2,其中 1 代表上部煤层,2 代表下部煤层;

  • ρ——井筒中液柱的密度,g/cm3

  • 参考文献

    • [1] QIN Y,MOORE T A,SHEN J,et al.Resources and geology of coalbed methane in China:a review[J].International Geology Review,2018,60(5/6):777-812.

    • [2] 徐宏杰,桑树勋,杨景芬,等.贵州省煤层气勘探开发现状与展望[J].煤炭科学技术,2016,44(2):1-7,196.XU Hongjie,SANG Shuxun,YANG Jingfen,et al.Status and expectation on coalbed methane exploration and development in Guizhou Province[J].Coal Science and Technology,2016,44(2):1-7,196.

    • [3] 国土资源部油气资源战略研究中心.全国煤层气资源评价 [M].北京:中国大地出版社,2009.Strategic Research Center of Oil and Gas Resources,Ministry of Land and Resources.Assessment of coalbed methane[M].Beijing:China Land Press,2009.

    • [4] 高弟,秦勇,易同生.论贵州煤层气地质特点与勘探开发战略 [J].中国煤炭地质,2009,21(3):20-23.GAO Di,QIN Yong,YI Tongsheng.Geological condition,exploration and exploitation strategy of coal-bed methane resources in Guizhou,China[J].Coal Geology of China,2009,21(3):20-23.

    • [5] 秦勇,熊孟辉,易同生,等.论多层叠置独立含煤层气系统—— 以贵州织金—纳雍煤田水公河向斜为例[J].地质论评,2008,54(1):65-70.QIN Yong,XIONG Menghui,YI Tongsheng,et al.On unattached multiple superposed coalbed-methane system:in a case of the Shuigonghe syncline,Zhijin-Nayong coalfield,Guizhou[J].Geology Review,2008,54(1):65-70.

    • [6] 秦勇,申建,沈玉林.叠置含气系统共采兼容性:煤系“三气”及深部煤层气开采中的共性地质问题[J].煤炭学报,2016,41(1):14-23.QIN Yong,SHEN Jian,SHEN Yulin.Joint mining compatibility of superposed gas-bearing systems:A general geological problem for extraction of three natural gases and deep CBM in coal series [J].Journal of China Coal Society,2016,41(1):14-23.

    • [7] 吴财芳,刘小磊,张莎莎.滇东黔西多煤层地区煤层气“层次递阶”地质选区指标体系构建[J].煤炭学报,2018,43(6):1 647-1 653.WU Caifang,LIU Xiaolei,ZHANG Shasha.Construction of index system of“Hierarchical progressive”geological selection of coalbed methane in multiple seam area of eastern Yunnan and western Guizhou[J].Journal of China Coal Society,2018,43(6):1 647-1 653.

    • [8] 杨兆彪,张争光,秦勇,等.多煤层条件下煤层气开发产层组合优化方法[J].石油勘探与开发,2018,45(2):297-304.YANG Zhaobiao,ZHANG Zhengguang,QIN Yong,et al.Optimization methods of production layer combination for coalbed methane development in multi-coal seams[J].Petroleum Exploration and Development,2018,45(2):297-304.

    • [9] 秦勇,吴建光,申建,等.煤系气合采地质技术前缘性探索[J].煤炭学报,2018,43(6):1 504-1 516.QIN Yong,WU Jianguang,SHEN Jian,et al.Frontier research of geological technology for coal measure gas joint-mining[J].Journal of China Coal Society,2018,43(6):1 504-1 516.

    • [10] 周效志,桑树勋,易同生,等.煤层气合层开发上部产层暴露的伤害机理[J].天然气工业,2016,36(6):52-59.ZHOU Xiaozhi,SANG Shuxun,YI Tongsheng,et al.Damage mechanism of upper exposed producing layers during CBM multi-coal seam development[J].Natural Gas Industry,2016,36(6):52-59.

    • [11] 张政,秦勇,WANG Guoxiong,等.基于等温吸附实验的煤层气解吸阶段数值描述[J].中国科学:地球科学,2013,43(8):1 352-1 358.ZHANG Zheng,QIN Yong,WANG Guoxiong,et al.Numerical description of coalbed methane desorption stages based on isothermal adsorption experiment[J].Scientia Sinica:Terrae,2013,43(8):1 352-1 358.

    • [12] 孟艳军,汤达祯,许浩,等.煤层气解吸阶段划分方法及其意义 [J].石油勘探与开发,2014,41(5):612-617.MENG Yanjun,TANG Dazhen,XU Hao,et al.Division of coalbed methane desorption stages and its significance[J].Petroleum Exploration and Development,2014,41(5):612-617.

    • [13] 康永尚,王金,姜杉钰,等.量化指标在煤层气开发潜力定量评价中的应用[J].石油学报,2017,38(6):677-686.KANG Yongshang,WANG Jin,JIANG Shanyu,et al.Application of quantitative indexes in quantitative evaluation of coalbed methane development potential[J].Acta Petrolei Sinica,2017,38(6):677-686.

    • [14] 秦勇,郑长东,王博洋,等.基于等温吸附曲线的煤储层产气潜力定量评价——以黔北地区长岗矿区为例[J].天然气工业,2018,38(9):40-47.QIN Yong,ZHENG Changdong,WANG Boyang,et al.Quantitative evaluation on the gas production potential of coal reservoirs based on isothermal adsorption curves:A case study of the Changgang Field,northern Guizhou,China[J].Natural Gas Industry,2018,38(9):40-47.

    • [15] LANGMUIR I.The constitution and fundamental properties of solids and liquids[J].Journal of the American Chemical Society,1916,38(11):1 553-1 564.

    • [16] 易同生,高为.六盘水煤田上二叠统煤系气成藏特征及共探共采方向[J].煤炭学报,2018,43(6):1 553-1 564.YI Tongsheng,GAO Wei.Reservoir formation characteristics as well as co-exploration and co-mining orientation of Upper Permian coal-bearing gas in Liupanshui Coalfield[J].Journal of China Coal Society,2018,43(6):1 553-1 564.

    • [17] THOMMES M,CYCHOSZ K A.Physical adsorption characterization of nanoporous materials:progress and challenges[J].Adsorption,2014,2(2/3):233-250.

    • [18] 周军平,鲜学福,姜永东,等.考虑有效应力和煤基质收缩效应的渗透率模型[J].西南石油大学学报:自然科学版,2009,31(1):4-8.ZHOU Junping,XIAN Xuefu,JIANG Yongdong,et al.A permeability model considering the effective stress and coal matrix shrinking effect[J].Journal of Southwest Petroleum University:Science & Technology Edition,2009,31(1):4-8.

    • [19] 张先敏,同登科,孙宝全.考虑基质收缩效应的致密煤储层数值模拟[J].应用基础与工程科学学报,2009,17(5):690-696.ZHANG Xianmin,TONG Dengke,SUN Baoquan.Numerical simulation of tight coalbed methane reservoir with the matrix shrinkage effect[J].Journal of Basic Science and Engineering,2009,17(5):690-696.

    • [20] 秦勇.叠置含气系统煤层气开发地质单元与开发方式[R].成都:国家科技重大专项课题年度报告会,2018.QIN Yong.Development methods and development geological unit for superposed CBM-bearing system[R].Chengdu:Annual Report of National Science and Technology Major Projects,2018.

    • [21] 胡海洋,赵凌云,陈捷,等.基于煤储层可采性的多煤层合采开发层段优选——以黔西地区发耳矿区为例[J].断块油气田,2019,26(6):775-779.HU Haiyang,ZHAO Lingyun,CHEN Jie,et al.Optimum selection of multi-seam development based on coal reservoir mineability:a case study of western Guizhou Fa’er ming area[J].Fault-Block Oil and Gas Field,2019,26(6):775-779.

    • [22] 胡海洋,赵凌云,金军,等.黔西煤层应力敏感性及对煤层气井排采的影响[J].断块油气田,2019,26(4):475-479.HU Haiyang,ZHAO Lingyun,JIN Jun,et al.Stress sensitivity of western Guizhou coal reservoir and its influence on drainage of CBM well[J].Fault-Block Oil and Gas Field,2019,26(4):475-479.

    • [23] 李陈,赵刚,陈丽群.考虑基质收缩效应的煤层气藏产能评价 [J].特种油气藏,2019,26(1):106-110.LI Chen,ZHAO Gang,CHEN Liqun.Productivity evaluation of coalbed methane reservoir with matrix shrinkage effect[J].Special Oil & Gas Reservoirs,2019,26(1):106-110.

    • [24] 闫霞,温声明,聂志宏,等.影响煤层气开发效果的地质因素再认识[J].断块油气田,2020,27(3):375-380.YAN Xia,WEN Shengming,NIE Zhihong,et al.Re-recognition of geological factors affecting coalbed methane development effect [J].Fault-Block Oil and Gas Field,2020,27(3):375-380.

    • [25] 王镜惠,王美冬,田锋,等.高煤阶煤层气储层产气能力定量评价[J].油气地质与采收率,2019,26(4):105-110.WANG Jinghui,WANG Meidong,TIAN Feng,et al.Quantitative evaluation of production capacity of high rank coalbed methane reservoir[J].Petroleum Geology and Recovery Efficiency,2019,26(4):105-110.

    • [26] 郭晨,卢玲玲.黔西煤层气成藏特性空间分异及其对开发的启示[J].煤炭学报,2016,41(8):2 006-2 016.GUO Chen,LU Lingling.Spatial distribution and variation of coalbed methane reservoir characteristics and its significance for CBM development in Western Guizhou[J].Journal of China Coal Society,2016,41(8):2 006-2 016.

    • [27] 曾毅.限流压裂工艺在织金煤层气开发中的应用[J].油气藏评价与开发,2014,4(3):73-77.ZENG Yi.Application of limited entry fracturing technology in CBM development of Zhijin area[J].Reservoir Evaluation and Development,2014,4(3):73-77.

  • 参考文献

    • [1] QIN Y,MOORE T A,SHEN J,et al.Resources and geology of coalbed methane in China:a review[J].International Geology Review,2018,60(5/6):777-812.

    • [2] 徐宏杰,桑树勋,杨景芬,等.贵州省煤层气勘探开发现状与展望[J].煤炭科学技术,2016,44(2):1-7,196.XU Hongjie,SANG Shuxun,YANG Jingfen,et al.Status and expectation on coalbed methane exploration and development in Guizhou Province[J].Coal Science and Technology,2016,44(2):1-7,196.

    • [3] 国土资源部油气资源战略研究中心.全国煤层气资源评价 [M].北京:中国大地出版社,2009.Strategic Research Center of Oil and Gas Resources,Ministry of Land and Resources.Assessment of coalbed methane[M].Beijing:China Land Press,2009.

    • [4] 高弟,秦勇,易同生.论贵州煤层气地质特点与勘探开发战略 [J].中国煤炭地质,2009,21(3):20-23.GAO Di,QIN Yong,YI Tongsheng.Geological condition,exploration and exploitation strategy of coal-bed methane resources in Guizhou,China[J].Coal Geology of China,2009,21(3):20-23.

    • [5] 秦勇,熊孟辉,易同生,等.论多层叠置独立含煤层气系统—— 以贵州织金—纳雍煤田水公河向斜为例[J].地质论评,2008,54(1):65-70.QIN Yong,XIONG Menghui,YI Tongsheng,et al.On unattached multiple superposed coalbed-methane system:in a case of the Shuigonghe syncline,Zhijin-Nayong coalfield,Guizhou[J].Geology Review,2008,54(1):65-70.

    • [6] 秦勇,申建,沈玉林.叠置含气系统共采兼容性:煤系“三气”及深部煤层气开采中的共性地质问题[J].煤炭学报,2016,41(1):14-23.QIN Yong,SHEN Jian,SHEN Yulin.Joint mining compatibility of superposed gas-bearing systems:A general geological problem for extraction of three natural gases and deep CBM in coal series [J].Journal of China Coal Society,2016,41(1):14-23.

    • [7] 吴财芳,刘小磊,张莎莎.滇东黔西多煤层地区煤层气“层次递阶”地质选区指标体系构建[J].煤炭学报,2018,43(6):1 647-1 653.WU Caifang,LIU Xiaolei,ZHANG Shasha.Construction of index system of“Hierarchical progressive”geological selection of coalbed methane in multiple seam area of eastern Yunnan and western Guizhou[J].Journal of China Coal Society,2018,43(6):1 647-1 653.

    • [8] 杨兆彪,张争光,秦勇,等.多煤层条件下煤层气开发产层组合优化方法[J].石油勘探与开发,2018,45(2):297-304.YANG Zhaobiao,ZHANG Zhengguang,QIN Yong,et al.Optimization methods of production layer combination for coalbed methane development in multi-coal seams[J].Petroleum Exploration and Development,2018,45(2):297-304.

    • [9] 秦勇,吴建光,申建,等.煤系气合采地质技术前缘性探索[J].煤炭学报,2018,43(6):1 504-1 516.QIN Yong,WU Jianguang,SHEN Jian,et al.Frontier research of geological technology for coal measure gas joint-mining[J].Journal of China Coal Society,2018,43(6):1 504-1 516.

    • [10] 周效志,桑树勋,易同生,等.煤层气合层开发上部产层暴露的伤害机理[J].天然气工业,2016,36(6):52-59.ZHOU Xiaozhi,SANG Shuxun,YI Tongsheng,et al.Damage mechanism of upper exposed producing layers during CBM multi-coal seam development[J].Natural Gas Industry,2016,36(6):52-59.

    • [11] 张政,秦勇,WANG Guoxiong,等.基于等温吸附实验的煤层气解吸阶段数值描述[J].中国科学:地球科学,2013,43(8):1 352-1 358.ZHANG Zheng,QIN Yong,WANG Guoxiong,et al.Numerical description of coalbed methane desorption stages based on isothermal adsorption experiment[J].Scientia Sinica:Terrae,2013,43(8):1 352-1 358.

    • [12] 孟艳军,汤达祯,许浩,等.煤层气解吸阶段划分方法及其意义 [J].石油勘探与开发,2014,41(5):612-617.MENG Yanjun,TANG Dazhen,XU Hao,et al.Division of coalbed methane desorption stages and its significance[J].Petroleum Exploration and Development,2014,41(5):612-617.

    • [13] 康永尚,王金,姜杉钰,等.量化指标在煤层气开发潜力定量评价中的应用[J].石油学报,2017,38(6):677-686.KANG Yongshang,WANG Jin,JIANG Shanyu,et al.Application of quantitative indexes in quantitative evaluation of coalbed methane development potential[J].Acta Petrolei Sinica,2017,38(6):677-686.

    • [14] 秦勇,郑长东,王博洋,等.基于等温吸附曲线的煤储层产气潜力定量评价——以黔北地区长岗矿区为例[J].天然气工业,2018,38(9):40-47.QIN Yong,ZHENG Changdong,WANG Boyang,et al.Quantitative evaluation on the gas production potential of coal reservoirs based on isothermal adsorption curves:A case study of the Changgang Field,northern Guizhou,China[J].Natural Gas Industry,2018,38(9):40-47.

    • [15] LANGMUIR I.The constitution and fundamental properties of solids and liquids[J].Journal of the American Chemical Society,1916,38(11):1 553-1 564.

    • [16] 易同生,高为.六盘水煤田上二叠统煤系气成藏特征及共探共采方向[J].煤炭学报,2018,43(6):1 553-1 564.YI Tongsheng,GAO Wei.Reservoir formation characteristics as well as co-exploration and co-mining orientation of Upper Permian coal-bearing gas in Liupanshui Coalfield[J].Journal of China Coal Society,2018,43(6):1 553-1 564.

    • [17] THOMMES M,CYCHOSZ K A.Physical adsorption characterization of nanoporous materials:progress and challenges[J].Adsorption,2014,2(2/3):233-250.

    • [18] 周军平,鲜学福,姜永东,等.考虑有效应力和煤基质收缩效应的渗透率模型[J].西南石油大学学报:自然科学版,2009,31(1):4-8.ZHOU Junping,XIAN Xuefu,JIANG Yongdong,et al.A permeability model considering the effective stress and coal matrix shrinking effect[J].Journal of Southwest Petroleum University:Science & Technology Edition,2009,31(1):4-8.

    • [19] 张先敏,同登科,孙宝全.考虑基质收缩效应的致密煤储层数值模拟[J].应用基础与工程科学学报,2009,17(5):690-696.ZHANG Xianmin,TONG Dengke,SUN Baoquan.Numerical simulation of tight coalbed methane reservoir with the matrix shrinkage effect[J].Journal of Basic Science and Engineering,2009,17(5):690-696.

    • [20] 秦勇.叠置含气系统煤层气开发地质单元与开发方式[R].成都:国家科技重大专项课题年度报告会,2018.QIN Yong.Development methods and development geological unit for superposed CBM-bearing system[R].Chengdu:Annual Report of National Science and Technology Major Projects,2018.

    • [21] 胡海洋,赵凌云,陈捷,等.基于煤储层可采性的多煤层合采开发层段优选——以黔西地区发耳矿区为例[J].断块油气田,2019,26(6):775-779.HU Haiyang,ZHAO Lingyun,CHEN Jie,et al.Optimum selection of multi-seam development based on coal reservoir mineability:a case study of western Guizhou Fa’er ming area[J].Fault-Block Oil and Gas Field,2019,26(6):775-779.

    • [22] 胡海洋,赵凌云,金军,等.黔西煤层应力敏感性及对煤层气井排采的影响[J].断块油气田,2019,26(4):475-479.HU Haiyang,ZHAO Lingyun,JIN Jun,et al.Stress sensitivity of western Guizhou coal reservoir and its influence on drainage of CBM well[J].Fault-Block Oil and Gas Field,2019,26(4):475-479.

    • [23] 李陈,赵刚,陈丽群.考虑基质收缩效应的煤层气藏产能评价 [J].特种油气藏,2019,26(1):106-110.LI Chen,ZHAO Gang,CHEN Liqun.Productivity evaluation of coalbed methane reservoir with matrix shrinkage effect[J].Special Oil & Gas Reservoirs,2019,26(1):106-110.

    • [24] 闫霞,温声明,聂志宏,等.影响煤层气开发效果的地质因素再认识[J].断块油气田,2020,27(3):375-380.YAN Xia,WEN Shengming,NIE Zhihong,et al.Re-recognition of geological factors affecting coalbed methane development effect [J].Fault-Block Oil and Gas Field,2020,27(3):375-380.

    • [25] 王镜惠,王美冬,田锋,等.高煤阶煤层气储层产气能力定量评价[J].油气地质与采收率,2019,26(4):105-110.WANG Jinghui,WANG Meidong,TIAN Feng,et al.Quantitative evaluation of production capacity of high rank coalbed methane reservoir[J].Petroleum Geology and Recovery Efficiency,2019,26(4):105-110.

    • [26] 郭晨,卢玲玲.黔西煤层气成藏特性空间分异及其对开发的启示[J].煤炭学报,2016,41(8):2 006-2 016.GUO Chen,LU Lingling.Spatial distribution and variation of coalbed methane reservoir characteristics and its significance for CBM development in Western Guizhou[J].Journal of China Coal Society,2016,41(8):2 006-2 016.

    • [27] 曾毅.限流压裂工艺在织金煤层气开发中的应用[J].油气藏评价与开发,2014,4(3):73-77.ZENG Yi.Application of limited entry fracturing technology in CBM development of Zhijin area[J].Reservoir Evaluation and Development,2014,4(3):73-77.

  • ×
    《油气地质与采收率》
    《油气地质与采收率》启动新投稿网站的公告