【作者】 刘会虎；

【导师】 桑树勋；

【作者基本信息】 中国矿业大学 ， 地球化学， 2011， 博士

【摘要】 以沁水盆地南部煤层气生产区为例,以生产井区流体化学场监测与系统的流体地球化学分析测试为技术手段,在煤层气生产区煤储层地质背景、煤层气井压裂和排采条件的基础上,研究了不同生产时刻煤层气组分、煤层气甲烷碳、氢同位素、地层水中离子浓度、地层水中元素含量,分析了煤层气组分、煤层气甲烷同位素、地层水中离子、地层水中元素的空间演化及其影响因素,探讨了不同流体化学场与井网排采条件下井间干扰的耦合关系,阐明了井间干扰的地球化学响应机理,提出了煤层气组分、甲烷同位素、地层水中离子及元素约束井间干扰的地球化学模式。本次研究取得的主要研究成果如下:(1)建立了煤层气井网排采井间干扰地球化学监测方法体系以现代地球化学测试分析为手段,对煤层气组分含量、煤层气稳定同位素比值(甲烷碳、氢同位素比值)、地层水中离子浓度、地层水中元素含量进行测试分析,较好地实现了对煤层气井间干扰阶段及程度的判断,首次确立了煤层气井网排采井间干扰的地球化学监测方法体系。(2)揭示煤层气排采流体化学场、动力场特征演化及其耦合关系煤层气井产水能力受煤储层渗透率、地层水位及排采工作制度的影响,产气量受煤层含气性、储层物性、地质构造、压裂效果及排采工作制度的影响;未产气前,井底流压主要由液柱压力控制,产气后主要受套压控制;套压、液柱压力、井底流压均与累计排水量、日产气量呈一定相关性;地下水流体势整体上由东向西及由南向北降低,监测时段内储层压力经历了反转期、分异期及不均衡压降期3个阶段,与煤层气生产的无井间干扰期、弱井间干扰期及不均衡井间干扰期相对应;在生产监测区内初步形成了井间干扰,且井间干扰处于不均衡井间干扰期,干扰程度相对较弱。煤层气组分、煤层气稳定同位素、地层水的总矿化度、地层水电导率、地层水碳酸盐硬度、地层水中元素含量呈周期性波动变化;地层水水化学类型主要为Na-HCO3型,部分井在局部生产时段产出地层水为Na-Cl型;不同采样时刻排出地层水的来源为煤层水、煤层水与砂岩水的混合水;煤层气组分和稳定同位素变化与煤层气组分分馏、同位素分馏、排采速率及井间干扰有关,产出地层水的离子浓度、矿化度、硬度及元素含量变化与煤层气井排采强度、井间干扰、物源及元素自身的性质有关。煤层气组分、稳定同位素的波动性变化、离子浓度整体变化的一致性反映了区域性井间干扰的影响。煤层气甲烷组分和二氧化碳组分的空间展布方向在采样时段内均多次改变,组分浓度的空间展布受局部煤层气产出组分浓度的影响;煤层气稳定同位素的空间展布主要经历了南北向展布及东西偏转的过程,碳、氢同位素的空间展布具有相似性,甲烷氢同位素的演化滞后于碳同位素;组分浓度差异及碳、氢同位素差异缩小揭示了井间干扰的影响,组分及同位素空间演化的多变性揭示了井间干扰处于初期且干扰程度较弱;地层水离子、元素的空间展布整体均表现出南北向及东西向的周期性偏转,矿化度的空间展布表现为由南向北降低,不如离子浓度的空间演化对井间干扰敏感,元素的演化滞后于离子的演化;离子、元素的空间演化及两者演化不一致的原因可能有:元素及离子本身的性质、物源影响、排采井间干扰的影响,甲烷组分浓度的空间展布与二氧化碳组分浓度的空间展布的叠合揭示二者的分布及演化基本不同步,不同步的原因主要与煤层气发生组分分馏及不均衡井间干扰期形成的不稳定流场产生气源补给的变化有关;煤层气甲烷碳、氢同位素比值的空间演化具有一致性,但氢同位素的空间演化滞后于甲烷碳同位素;甲烷组分浓度的空间演化与甲烷碳同位素比值的空间演化的叠合表明两者演化并不完全同步,主要与煤层气组分分馏、同位素分馏、井网排采条件气源的补给及地下水动力条件的改变有关。不同液相流体参数之间的叠合分析显示两者在空间叠迭上并不完全一致,主要原因可能为:地层水中离子与元素的性质、井网排采过程与井间干扰的作用、地层水来源的不同;不同液相流体参数之间的叠合揭示了两者不同步的真正原因为井间干扰初级阶段的不稳定性;气相流体化学场与液相流体化学场的演化具有明显的一致性,明显受井间干扰的影响,两者耦合时表现出明显的正相关。不同相态流体化学场中参数的空间演化与煤层构造、煤储层压裂裂缝主缝长的叠合关系分析揭示了排采的流体化学场与煤层构造及压裂主裂缝的缝长没有直接的联系,进一步揭示了流体化学场方向的变化是由排采所形成的井间干扰引起的。(3)建立了煤层气排采井间干扰地球化学响应模式井网排采的流体化学参数、流体化学场与井间干扰存在响应关系,流体化学参数表现出的波动变化特征,对井间干扰的形成过程起到响应作用,流体化学场的分布特征及演化特征对井间干扰的不同阶段均有不同的响应。在排采初期未形成井间干扰阶段,煤层气中轻组分先升后降,重组分先降后升,稳定同位素先偏轻后偏重,绝大部分离子浓度、矿化度、电导率、元素含量先升后降,同一生产时刻不同煤层气井产出煤层气的组分、稳定同位素、离子浓度、元素含量、矿化度、电导率等差异明显;井间干扰初步形成阶段,煤层气组分、稳定同位素及绝大部分离子浓度、矿化度、电导率、元素含量呈周期性波动上升与下降,同一生产时刻不同煤层气井产出煤层气的组分、稳定同位素、离子浓度、元素含量、矿化度、电导率差异减小;井间干扰稳定阶段,煤层气组分及稳定同位素仍呈波动性周期变化,不同煤层气产出的煤层气组分及稳定同位素具有趋同效应,组分及同位素的变化规律具有同步性,离子浓度、矿化度、电导率、元素含量变化呈周期性波动,邻井产出地层水中离子浓度、元素含量变化具有同步性,远井表现出变化相似性。气相流体化学场通过发生偏转或倒转,响应煤层气来源的多源性及网排采下井间干扰过程;不同组分的空间演化关系通过叠合时叠迭关系交错或重叠反映其它煤层气来源的影响,从而响应井间干扰;不同液相流体化学参数的空间演化关系通过叠合时叠迭关系的变化反映不同地层水来源,从而响应井网排采条件下井间干扰过程。(4)科学评估了煤层气生产井区井间干扰作用及其生产控制以煤层气排采流体动力场、流体化学参数及化学场为基础,确立了煤层气井生产井区井间干扰评价的原则和方案,判定了煤层气生产区排采井间干扰阶段及程度,评价方案能适用于不同煤层气生产区,为煤层气开发提供了生产控制上的技术支撑。该论文有图80幅,表12个,参考文献169篇。更多还原

【Abstract】 With CBM production of southern Qinshui basin as an example, the fluid geochemical field of the production well area and systematic testing and analysis of geochemistry was chosen as technical method. Based on geological setting of coal reservoir, fracturing and drainage of CBM well in CBM production area, CBM components, CBM carbon and hydrogen isotopes, ion concentration of formation water, element content of formation were studied. The spatial evolutions and affecting factors of CBM components, CBM methane isotopes, ion concentration, and element content were analyzed. Coupled relation of different fluid chemical field and well interference during drainage under well pattern was discussed, the constrained mechanism of well interference was illustrated, and the geochemical response model on well interference from CBM components, methane carbon and hydrogen isotopes, ion and element of formation water were proposed. The main research achievements are concluded as follows:(1) Geochemical monitoring method of well interference during drainage under well pattern was established.The modern geochemical testing and analysis was chosen as the method. The content of CBM components, the ratio of stable isotope of CBM, ion concentration of formation, element content of formation water were tested and analyzed, the stage and the degree of well interference of CBM wells were distinguished, geochemical monitoring method of well interference during drainage of CBM under well pattern was established.(2)The evolution characteristics and coupled relation of fluid chemical field, fluid dynamic field during drainage of CBM wells were revealed.Flowing bottom-hole pressure is controlled by Hydrostatic pressure before gas generation, but is controlled by casing pressure after gas generation. Casing pressure, hydrostatic pressure, flowing bottom-hole pressure have a certain correlation with accumulative water drainage. The underground water flows from the east to the west and from the south to the north. Coal reservoir pressure undergoes three stages: reversal period, differential period, unbalanced pressure drop period in monitoring time; it is correspond to the period of without well-interference, weak well-interference period, unbalanced well-interferenced period of CBM production. The well-interference occurs, but the well interference is unbalanced, may be in the initial stage, and its interference is relatively weak. CBM components, methane carbon and hydrogen isotopes, the ion concentration, total mineralization, the conductivity, the hardness, the element content have cyclical fluctuation with drainage time. Hydrochemical types of formation water from different CBM wells are mainly Na-HCO3, but partial hydrochemical type of formation water of partial CBM wells are Na-Cl with some special period, the sources of formation water are mainly coalbed water, the mixed water of coalbed water and sandrock water. The fluctuation of CBM components, the stable isotopes of methane may be related to component fractionation, isotope fractionation, drainage and well interference. The fluctuation of ion concentration, the mineralization, the conductivity, the hardness and the element content may be associated with drainage of CBM wells, well interference, the source of formation water, the properties of element and ion. The fractionation of CBM components, the stable isotopes, and the consistency of the variation of ion concentration reflects the effect from well interference.The spatial distribution of methane, carbon dioxide undergoes several changes in the sampling period. The spatial distribution of the concentration of CBM components is affected by the concentration of CBM produced by partial wells. The spatial evolution of the stable isotopes of CBM undergoes the course the distribution of the north-south and the deflection of the east-worth. The spatial distribution of carbon isotope is similar to the spatial distribution of hydrogen isotope, the evolution of methane hydrogen isotope falls behind methane carbon isotope. The decreasing difference of CBM components, methane carbon and hydrogen isotopes reveal the effect of well interference. The variability of the spatial evolution of CBM components and methane isotopes reveal that well interference in the initial stage, and the interference. The spatial distribution ion, element of formation water is characterized by cyclical deflection with the NS trending and the ES trending. The spatial distribution of the mineralization decrease from the south to the north, it is not sensitive than the spatial evolution of ion concentration on well interference, the spatial evolution of element falls behind the spatial evolution of ion. The spatial evolution of ion and element, their inconsistency are related to the properties of ions and elements, the source of formation water, well interference.The composite between the spatial distribution of methane and carbon dioxide shows the distribution and evolution of them is basically asynchronous, because the spatial distribution of methane and carbon dioxide are mainly related to component fractionation of CBM, the supply of CBM caused by the instable fluid field in the initial stage of well interference. The spatial evolution of carbon isotope ratio is consistent with the spatial evolution of hydrogen isotope ratio, but the spatial evolution of hydrogen isotope lags behind the spatial evolution. The composite relation of the spatial evolution of CBM component is consitent with the spatial evolution of methane carbon isotope demonstrates, which is related to component fractionation of CBM, isotope fractionation, the supply of gas source and the change of hydrodynamic condition of ground water.The composite analysis of different liquid fluid parameters show there are not entirely consistent in the spatial distribution of the two parameters of liquid fluid, the main reason may be related to the properties of ion and element, drainage under well pattern, well interference, the different source of formation water. The composite analysis between different liquid phase fluids also reveals the real reason of the inconsistency of different liquid phase fluid is the instability of the initial well interference. The evolution of chemical field of gas phase fluid is obviously consistent with the evolution of chemical field of liquid phase fluid, they are affected by well interference obviously, and there is an obvious positive correlation between them during coupling.That fluid chemical field is not related to the structure of coal bed directly, the length of main artificial fracture by fracturing, which reveals the variation of fluid chemical field is caused by well interference formed by drainage.(3) The geochemical response model of well interference during drainage of CBM was established.There is a response relationship between fluid chemical parameters, fluid chemical fields and well interference, fluctuation change characteristics of fluid chemical parameters responds the forming process of well interference, the distribution characteristics of fluid chemical field and evolution characteristics of fluid chemical flied also respond the different stages of well interference. The deflection and the inversion of chemical field of chemical field reflect the multiple sources of CBM, response the course of well interference.(4) The action of well interference in CBM production area and its production was assessed scientifically.On the basis of fluid dynamic field, fluid chemical parameters and chemical field during drainage of CBM, the principle and the scheme of assessment on well interference of CBM wells in production area, the stage and the degree of well interference in CBM production area during drainage was judged. The assessment scheme can apply to different CBM production area; it can provide the technical support for CBM development in production control.更多还原