天津滨海新区地热资源循环利用研究——馆陶组热储回灌技术研究与示范

可持续回灌是地热资源循环采用的基本。本文通过热储敏感性、堵塞原因、成井结构以及地面装置分析了回灌衰减的原因。认为物理堵塞是回灌堵塞的主要原因,成井结构是维持可持续回灌的关键,标准的地面设备可避免由于物理和化学原因引起的堵塞。本文采用成功的成井结构和标准的地面装置开展馆陶组热储回灌地热资源循环采用的示范工程建设,回灌率达到100~123 m3/h,实现了天津滨海新区馆陶组热储回灌突破,保证了滨海新区馆陶组地热资源循环利用。     

东营市中心城区地热田地热回灌可行性分析

利用东营市中心城区鲁班公寓的地热生产井,对新近纪馆陶组和古近纪东营组热储层进行了自然压力条件下的异层和同层回灌试验。结果表明,回灌量与水头升高呈正相关关系,单位回灌量与水头升高呈负相关关系,馆陶组东热2井回灌能力为东营组东热。井的3倍左右。通过对该地热田热储地质条件、回灌能力及地热水开采潜力的分析,认为目前条件下东营城区还不适宜全面推行地热回灌。     

砂岩热储回灌对储层影响评价——以鲁西北坳陷地热区为例

地热流体经供暖利用后尾水温度降低,经过滤、排气处理后的尾水中仍含有不同粒径的悬浮物、气体,因此回灌不可避免的会对储层造成负面影响,如堵塞储层导致回灌量衰减、热储温度降低甚至产生热突破等,这严重阻碍了地热回灌的长期可持续运行。评价回灌对储层的影响,对下一步全面推进、科学回灌及合理可持续开发利用、保护地热资源具有重要意义。本文以近几年鲁西北坳陷区开展的馆陶组热储回灌试验为基础,设立了一套评价指标,即用回灌前、后水质的变化率评价回灌对热储流体的影响,温度的变化率评价回灌对热储温度的影响,单位涌水量变化率、渗透系数的比值和单位回灌量比值评价回灌堵塞程度并确定了分级标准。评价结果表明,回灌不会改变储层流体的化学类型;回灌堵塞主要发生在回灌井周围,相比回灌前,回灌后回灌井的单位涌水量降低14.3%～59.0%、渗透系数为原来的41%～86%,末期单位回灌量为初期回灌量的51%～92%,回灌堵塞程度为轻度到严重。采灌井距180～500m,历经一个供暖季回灌对热储温度的影响较小,但回灌导致回灌井周边热储温度明显降低,历经一个非回灌期224d,从35. 7℃恢复到40. 53℃,恢复速率为0. 036～0. 022℃/d,还需658d才能恢复到原热储温度(55℃)。本区热储水位仍呈下降趋势,但回灌可延缓热储水位的下降速度。     

新近系砂岩地热回灌堵塞问题的探讨

结合目前国内外普遍存在的砂岩地层回灌效率低的问题,文章剖析砂岩地层容易发生堵塞的地质构造特性,以及在回灌中由于水敏、速敏等作用引起储层物性变化,固体颗粒逐渐沉淀或被捕获,堵塞孔隙,渗流阻力增大,渗透率降低,使地热流体回灌能力减弱;分析当热储层的孔隙度一定时,不同基质颗粒的粒径成为影响地热流体产能和回灌的主要因素。总结目前在砂岩地层中常见堵塞的类型、成因分析以及解决各类堵塞的方法。     

基于Origin的渗透系数衰减方程在地热水回灌中的应用

孔隙型热储层的回灌过程中,由于物理堵塞、生物化学堵塞、悬浮物堵塞和气体堵塞,热储层的渗透性下降,回灌能力变弱.为了定量查明渗透系数的衰减,以辽南地区某回灌试验为例,使用Origin软件计算出研究区渗透系数衰减方程,在此基础上计算了回灌井灌压-时间关系曲线和回扬周期.研究表明,利用Origin软件求取渗透系数衰减方程具有方便快捷、规范性好等优点,可在回灌试验数据处理中推广使用.     

天津地区孔隙型热储层地热流体回灌影响因素探讨

文章通过对孔隙型热储层地热流体回灌试验中回灌量与液柱压力、流体温度相互关系等方面分析和探讨,认为其主要影响因素为热储层物质结构、水文地质特征、回灌水温度、成井工艺、回灌与开采井间的距离、回灌方式等条件。     

东濮凹陷西斜坡带优质砂岩热储特征研究

东濮凹陷西斜坡带新近系明化镇组砂岩热储地热井, 存在出砂严重和回灌困难的问题. 为了弄清东濮凹陷西斜坡带优质砂岩热储层地热地质特征, 综合考虑构造、储层和地温情况, 开展区域构造、地温场分布规律及热储精细解剖研究, 优化探井设计. 研究表明, 东濮凹陷西斜坡带新近系构造稳定, 馆陶组底板埋深2 000~2 200 m, 优质砂体发育在馆陶组下部1 800~2 200 m, 温度65℃以上, 热储物性较好, 具备地热资源开发潜力. 东濮凹陷西斜坡带长垣地区优化部署的馆陶组砂岩热储地热井试水结果与预测一致, 进一步证实了东濮凹陷西部斜坡带的地热勘探开发潜力.     

地下热水回灌过程中渗透系数研究

地下热水回灌是处理地热开发利用中所引发的热储层压力降低和弃水污染环境等问题的有效方法。第三系热储层的回灌过程中，由于物理阻塞和化学阻塞，导致热储层的渗透性下降。回扬可在短时间内消除或缓解堵塞问题，提高回灌效率。将利用回灌试验数据求得的渗透系数进行回归，得到渗透系数衰减方程。用数值方法模拟渗透系数对回灌的影响，对比渗透系数为常数与渗透系数变化两种情况，结果表明渗透系数衰减是第三系回灌能力下降的主要原因，渗透系数是影响回灌的重要因素。     

配伍性实验在西安市地热水回灌试验中的应用

西安市地热田储层为砂岩孔隙型储层,孔隙度和渗透率都比较低,很容易发生回灌堵塞现象。对西安市同层回灌水和异层回灌水的配伍性进行研究,配伍性实验结果表明:西安市地热尾水回灌到回灌井后主要的结垢类型为CaCO3,结垢量小于100 mg/L,配伍性较好,不会大量结垢而导致地热储层堵塞。     

东营市城区馆陶组热储回灌性能分析

东营市城区馆陶组热储为新近系松散碎屑岩层状热储,目前地热资源开采量约95万m3/a,回灌是解决热储压力下降与地热尾水排放对环境造成不良影响的最佳措施,该文采用自然回灌试验方法探讨回灌条件下馆陶组热储的渗透性能,并与德州市城区馆陶组热储压力回灌试验成果进行了对比,对该热储的回灌性能进行了分析,为指导该区地热回灌提供了科学依据。     

Hypothetical thermohaline transportation study of pumping-reinjection wells in the geothermal field

In the use of geothermal energy, the reinjection of heat-depleted brines is the most important issue. The reinjection of reservoir fluid can support reservoir pressures and also allow more efficient thermal energy recovery, but at the same time many problems occur during reinjection of heat-depleted brines, among which is the precipitation of the products of reactions between reinjected fluid and the reservoir’s fluid and solid constituents. We discuss the dynamics of the reinjection of heat-depleted brines into the original reservoir using a thermohaline theoretical model using FEFLOW software, representing the effect of the difference in temperature and concentration between heat-depleted brine and reservoir fluid, regardless of the chemical reactions and assuming clean brine.     

沉积盆地砂岩热储回灌试验研究——以山东禹城市为例

禹城市为东营组热储地热资源开采利用集中区,因地热资源集中开采及地热尾水的直接外排,造成了水化学污染、热污染及热储层压力下降等一系列地质环境问题。本次在禹城市地热资源开发利用现状调查的基础上,在禹城市栖庭水岸开展地热回灌试验研究,回灌模式为自然同层对井回灌。根据本次回灌试验取得的数据,对回灌量与回灌压力关系、回灌对热储层水质影响、回灌对热储层温度影响规律进行了分析研究并根据拟合回灌量与水位升幅关系曲线计算了最大回灌量。分析结果表明:回灌量随压力的增大而增大,单位回灌量随回灌压力的增大呈减小趋势;回灌井因灌入了矿化度比其自身地热水矿化度高的水源,所以回灌后采集的回灌井地热水矿化度比回灌试验之前高,但因采灌井开采热储层属于同层热储,故回灌对热储层水质影响小;本次试验采灌井间距较大,故回灌对热储层温度无影响;计算确定该回灌井最大回灌量为70 m~3/h。本次回灌试验研究为禹城市地热资源可持续开发利用提供了依据。     

天津市塘沽低温热储回灌的水-岩相互作用地球化学模拟

地球化学模拟是了解早期阶段回灌影响的有效方法,对塘沽热田的地热回灌试验进行了地球化学模拟,以地热供暖尾水作为初始反应流体,通过模拟其与储层岩石的水－岩相互作用,确定回灌对储层性质的影响,模拟是根据回灌水在不同温度下分别与岩石反应及在不断升温过程中连续与岩石相互作用而进行的,结果表明,回灌的影响在开始阶段是相当重要的,在仅考虑溶解和沉淀矿物间体积平衡的情况下,回灌对储层的孔隙度产生正的效应,水－岩相     

地热回灌防腐过滤器及配套技术试验

利用专题立项开凿的地热生产井和地热回灌井,对第三纪孔隙型热储层进行了加压条件下的对井同层回灌试验。通过研发地热回灌防腐过滤器及配套技术,解决了先前在回灌过程中由各种物理、化学和生物因素引起的堵塞,导致回灌量减小、回灌井早期丧失回灌能力这一技术难题。     

鲁北地区砂岩热储地热尾水回灌地温场变化特征分析

本文通过对德州水文家园砂岩热储地热回灌井全井段温度监测,在深度上分为5个区段论述了地温场的变化特征,重点对热储温度恢复的热量来源进行了分析。研究结果表明,在规模化生产性回灌时,低温地热尾水回灌会使得回灌井周边热储温度明显降低,并且恢复速率特别缓慢;通过定性分析和定量计算,认为大地传导热流和顶部地层传导热流在热储温度恢复中的作用极其微弱,而外围同层相对高温地层传导的热量和地热水流动带来的热量是其温度恢复的主要热量来源。基于该研究结果,在规模化回灌条件下,发生热突破是必然的,因此深入开展回灌工程采灌井合理井距研究、防止短时间内发生热突破是非常有必要的。     

Constraints on the formation of cyclic units in ultramafic zones of large basaltic chambers

Petrological models for the formation of cyclic units in ultramafic zones at the base of large mafic layered intrusions are still few and simple. In this study, we develop simple physical constraints, such as the volume balance and density relationships between the various liquids involved. We consider the formation of an entire ultramafic zone, made of N cyclic units due to N successive reinjections. We tackle the following problems. Are all the injections of the same chemical composition? Are the N injections responsible for the formation of the whole magma chamber? Two end-member models are examined. In the first one, the chamber grows with each injection and does not lose any magma (variable volume model, VV). In the second one, the chamber initially forms with a large volume of magma and remains at a constant volume with subsequent reinjections of small volumes balanced by eruptions of equal volume (fixed volume model, FV). Several scenarios for the formation of a cyclic unit are envisioned. Petrological data such as thicknesses of the cumulate layers and their compositions, together with the fractionation density of the cumulate phases, allow the calculation of the density evolution, as a function of the initial density only. Thus, the model yields constraints on the density of the initial liquid, and hence on its chemical composition. The volumes of the injected magmas are calculated as well as the evolution of the densities of the different involved liquids. We apply the calculation to the specific case of the Ultramafic Series of the Stillwater complex. The multiple reinjection models require that the initial liquids densities vary between 2.71 and 2.72 g/cm³, corresponding to MgO-rich liquids for which there is no field evidence, either in dikes or in chilled margins. They also require that the source produces liquids of different chemical composition. Thus, the evolution of the igneous system requires another, larger reservoir where differentiation takes place prior to injection into the shallower one. Contrary to the multiple reinjection models, a closed system model where crystallization proceeds in an isolated bottom layer does not require any specific value of density for the liquids, provided, of course, that it is of basaltic composition. On the negative side, such a model is not supported by any physical processes which would account for the formation of cyclic units.     

西宁盆地地热水特征及回灌结垢风险

青海西宁盆地中低温地热资源丰富,但热储地层以含黏土矿物的弱胶结砂岩为主,地热水溶解性总固体较高,回灌过程中存在显著的结垢风险。基于对西宁盆地地热成因及资源分布特征分析,采用矿物溶解度法、饱和指数法等方法对典型地热水回灌结垢趋势及风险进行了综合判断。结果表明:西宁盆地“凹中凸”构造有利于地热水在深部热储富集和增温,同时将深部溶解的大量矿物质带到西宁地区中央凸起地带;西宁地区地热储层埋深主要在700～1600 m,水温30～70 ℃,主要为SO₄·Cl—Na水化学类型,溶解性总固体1.85×103～4.80×104 mg/L;回灌过程中结垢以碳酸钙结垢为主,当回灌水与地下热水性质相近时,结垢风险主要发生在回灌井筒中,地层结垢风险较小,而当回灌水与地下热水性质差异较大时,不配伍性将导致地层结垢风险大大提高,其中药王泉与DR2005原1∶ 1混合时结垢量最大可达177.57 mg/L,而其他地热水结垢量较小。根据以上特征,提出以下综合解决方案:物理防垢+管材防腐、系统增压防垢+管材防腐和地面预处理+管材防腐,并辅之以阴极保护防腐、优化排量、酸洗井筒等措施,可为今后保障地热水回灌能力措施的制定提供理论依据与技术支持。     

Study on the geothermal production and reinjection mode in Xiong County

The large karst geothermal field of Xiong County,which is located to the south of geothermal field in Niutuozhen,features huge geothermal resources and favorable condition for development and utilization.Because of the long-term extensive production,the pressure of geothermal reservoir continues to decline and some geothermal wells even face the danger of scrapping.To relieve the fall in pressure of geothermal reservoir and achieve the sustainable development and utilization of geothermal field in the long run,reinjection experiment is conducted in the geothermal field of Xiong County and a three-dimensional hydrothermal coupled numerical model was constructed.The reinjection experiment showed that the mode of one production well and one reinjection well can be achieved in this geothermal field.The numerical simulation is used to forecast and compare the change in pressure field and temperature field under different production and reinjection modes and concludes that the most opotimized production and utilization mode is the concentrated production-reinjection mode,and the most opotimized production-reinjection combination mode is the shallow production and shallow reinjection mode which can ensure the sustainable development and utilization of geothermal resources in the long run.     

新近系热储层回灌井钻探工艺探索

文章通过对新近系热储层回灌井成井结构进行室内模拟试验,探索了因回灌井自身结构特点不足而造成回灌不畅的原因,初步探讨了适合天津地区孔隙型回灌井的施工工艺及井身结构.     

Seepage-heat transfer coupling process of low temperature return water injected into geothermal reservoir in carbonate rocks in Xian County,China

Fracture seepage and heat transfer in the geothermal reservoir of carbonate rocks after the reinjection of low temperature geothermal return water is a complex coupling process,which is also the frontier of geothermal production and reinjection research. Based on the research of cascade comprehensive development of geothermal resources in Beijing-Tianjin-Hebei (Xian County),the carbonate geothermal reservoir of Wumishan formation in the geothermal field in Xian County is investigated. With the development of the discrete fracture network model and the coupling model of seepage and heat transfer,the numerical solution of seepage field and temperature field with known fracture network is reached using the finite element software COMSOL,and the coupling process of seepage flow and heat in carbonate rocks is revealed. The results show that the distribution of temperature field of fractured rocks in geothermal reservoir of carbonate rocks has strong non-uniformity and anisotropy. The fracture network is interpenetrated,which constitutes the dominant channel of water conduction,and along which the fissure water moves rapidly. Under the influence of convective heat transfer and conductive heat transfer,one of the main factors to be considered in the study of thermal breakthrough is to make the cold front move forward rapidly. When the reinjection and production process continues for a long time and the temperature of the geothermal reservoir on the pumping side drops to a low level,the temperature of bedrocks is still relatively high and continues to supply heat to the fissure water,so that the temperature of the thermal reservoir on the pumping side will not decrease rapidly to the water temperature at the inlet of reinjection,but will gradually decrease after a long period of time,showing an obvious long tail effect. The distribution of fractures will affect the process of seepage and heat transfer in carbonate reservoirs,which should be considered in the study of fluid thermal coupling in carbonate reservoirs.