CN1508389A - Coalbed Gas Thermal Exploitation Method - Google Patents

Abstract

Translated fromChinese

本发明公开了煤层气的热力开采方法，煤层甲烷气通常是以吸附状态存在于煤层孔隙表面的，它的产出至少要经过解吸、渗流两个过程，因而解吸速度和渗流速度是决定产气速度的主要因素。这种热力采气方法，通过热力驱方式注入热能，增加吸附态煤层气(甲烷)的自由能，从而增加甲烷从煤层孔隙表面上解吸的速度，同时气体受热膨胀加速渗流流动，从而达到大幅度提高煤层气产量、实现煤层气的工业化开发的目的。

The invention discloses a thermal mining method for coal bed methane. Coal bed methane gas usually exists on the coal seam pore surface in an adsorption state, and its output must go through at least two processes of desorption and seepage, so the desorption speed and seepage speed are the factors that determine gas production. The main factor of speed. In this thermal gas extraction method, thermal energy is injected through thermal driving to increase the free energy of adsorbed coalbed methane (methane), thereby increasing the desorption speed of methane from the coal seam pore surface, and at the same time, the expansion of gas by heating accelerates the seepage flow, thereby achieving a large The purpose of increasing the output of coalbed methane and realizing the industrialized development of coalbed methane.

Description

Translated fromChinese

煤层气的热力开采方法Coalbed Gas Thermal Exploitation Method

技术领域technical field

本发明涉及一种提高煤层气井产量、高速开发煤层气的方法和技术，特别是指煤层气的热力开采方法，属于煤炭化工技术领域。The invention relates to a method and technology for increasing the output of coalbed methane wells and developing coalbed methane at a high speed, in particular to a thermal mining method for coalbed methane, and belongs to the technical field of coal chemical industry.

背景技术Background technique

煤层甲烷气(Coal bed Methane)简称煤层气，煤矿称瓦斯或沼气，是成煤过程中形成的、仍以煤层为储集层的天然气，主要成分为甲烷(CH₄)。甲烷是宝贵的资源、优质的能源和化工原料，可作为常规天然气的接替能源或补充能源，但是，如果不预先开发煤层气，采煤过程中甲烷将进入矿井巷道而可能导致瓦斯爆炸事故，或作为废气排入大气、引起环境污染。因此，开发煤层气能充分利用宝贵的自然资源、防止煤矿瓦斯爆炸事故、保护大气环境。Coal bed methane (Coal bed methane) is referred to as coal bed methane, and coal mines are called gas or biogas. It is a natural gas formed during coal_formation and still uses coal seams as reservoirs. Methane is a valuable resource, high-quality energy and chemical raw material, which can be used as a replacement or supplementary energy source for conventional natural gas. However, if coalbed methane is not developed in advance, methane will enter the mine roadway during coal mining and may cause gas explosion accidents, or Exhausted into the atmosphere as waste gas, causing environmental pollution. Therefore, the development of coalbed methane can make full use of precious natural resources, prevent coal mine gas explosion accidents, and protect the atmospheric environment.

中国煤层气资源丰富，90年代开始有关公司借鉴美国成功开发煤层气的经验，开发煤层气，打井数百口，但试验效果不理想，主要问题是产量低(产气量超过1000米³/日的井仅占总钻井数的10％左右)、产量不稳定，不能达到工业化开发的标准。China is rich in coalbed methane resources. Since the 1990s, relevant companies have learned from the experience of successfully developing coalbed methane in the United States to develop coalbed methane and drill hundreds of wells, but the test results are not ideal. The main problem is low production (gas production exceeds 1000^m3 /day) The wells only account for about 10% of the total number of wells), and the output is unstable, which cannot meet the standards of industrial development.

试验表明，中国煤层气储层特点与其他国家不同，简单地照搬应用他国经验是行不通的，必须研制适合中国煤层特点的开发技术。Tests have shown that the characteristics of China's coalbed methane reservoirs are different from those of other countries, and it is not feasible to simply copy and apply the experience of other countries. It is necessary to develop development technologies suitable for the characteristics of China's coalbeds.

产气量小的原因主要为：与常规天然气相比，煤层气的储存方式以吸附为主、储层能量低(压力低)、渗透性差，煤层气的产出过程是首先降压解吸，然后在孔隙介质中渗流。由此可见煤层气的产出过程复杂，产量受解吸速度和渗流速度的制约，除非针对个别很高渗透性的储层，否则仅依靠天然能量较难获得很高的产气量和采收率，必须寻找和研究提高开采速度(或日产气量)和采收率的新方法。The main reasons for the small gas production are: compared with conventional natural gas, the storage method of coalbed methane is mainly adsorption, the reservoir energy is low (low pressure), and the permeability is poor. Seepage in porous media. It can be seen that the production process of coalbed methane is complicated, and the production is restricted by the desorption speed and seepage speed. Unless it is aimed at individual high-permeability reservoirs, it is difficult to obtain high gas production and recovery only by relying on natural energy. It is necessary to find and study new ways to increase the production rate (or daily gas production) and recovery.

常规石油天然气开采可以采用注水或注天然气的方法，增加地层压力和能量，达到驱替石油天然气、实现高速开采的目的。而对于煤层气，如果高压注水或注气，则煤层气体压力增高，由于甲烷是吸附态的，增加压力不利于解吸放出，甚至使已经解吸的游离气体再吸附。所以注水或注气致使煤层气无法解吸，只有降压才能解吸，因此采用高压注水、注气是不合适的。Conventional oil and gas extraction can use water injection or natural gas injection to increase formation pressure and energy to achieve the purpose of displacing oil and natural gas and realizing high-speed extraction. For coalbed methane, if water or gas is injected under high pressure, the pressure of coalbed gas will increase. Since methane is adsorbed, increasing the pressure is not conducive to desorption and release, and even desorbed free gas will be re-adsorbed. Therefore, water injection or gas injection cannot desorb coalbed methane, and desorption can only be achieved by depressurization, so it is not appropriate to use high-pressure water injection or gas injection.

目前，有一种针对煤层气的CO₂吸附法，该方法是利用CO₂具有比甲烷高的吸附性，注入CO₂后，排挤甲烷或改变其吸附特性。但这种方法还必须适当地降压，在降压过程中CH₄解吸，CO₂具有强吸附性而占据CH₄的位置，从而使CH₄保持游离状态。总的过程是：生产井开井降压，注入井注入CO₂，降压后甲烷解吸为游离状态，CO₂吸附。然后增加注入压力，甲烷无法吸附，只能沿孔隙流动从气井产出。生产一段时间后，再次降压，进行下一个循环的注入和产出。但由于降压过程在生产井，而CO₂是在注入井注入，所以CH₄与CO₂的竞争可能不同时发生，另外由于升压与降压的反复循环，因此也不能很大幅度地提高产气量。目前这只是一种理论上的方法。At present, there is a CO₂ adsorption method for coalbed methane, which uses CO₂ to have a higher adsorption than methane, and after CO₂ is injected, methane is displaced or its adsorption characteristics are changed. However, this method must also be properly depressurized. During the depressurization process, CH₄ desorbs, and CO₂ has strong adsorption and occupies the position of CH₄ , so that CH₄ remains in a free state. The overall process is: the production well is opened to reduce the pressure, the injection well is injected with CO₂ , after the pressure is reduced, the methane is desorbed into a free state, and the CO₂ is adsorbed. Then increase the injection pressure, methane cannot be adsorbed, and can only flow along the pores to be produced from the gas well. After a period of production, the pressure is lowered again for the injection and output of the next cycle. However, since the depressurization process is in the production well, and CO₂ is injected in the injection well, the competition between CH₄ and CO₂ may not occur at the same time. In addition, due to the repeated cycle of boosting and depressurizing, it cannot be greatly improved Gas production. This is only a theoretical approach for now.

通过研究发现，高温下CH₄的吸附能力大大降低，采用热力方法加热煤层可以增加CH₄的解吸速度，同时热能在向煤层传递的过程中气体受热膨胀，有利于建立生产压差，从而大幅度地增加气井日产量。当前，有热力开采稠油的专利，但没有把热力方法引入开采煤层气的先例。Through the research, it is found that the adsorption capacity of CH₄ is greatly reduced at high temperature, and the desorption rate of CH₄ can be increased by heating the coal seam with thermal methods. Increase the daily production of gas wells. At present, there are patents for thermal extraction of heavy oil, but there is no precedent for introducing thermal methods into the extraction of coalbed methane.

发明内容Contents of the invention

本发明的主要目的在于提供一种煤层气的热力开采方法，使煤层气产量得到提高。The main purpose of the present invention is to provide a thermal mining method of coal bed gas, so that the production of coal bed gas can be improved.

本发明的目的是通过如下技术方案实现的：The purpose of the present invention is achieved through the following technical solutions:

一种煤层气的热力开采方法，至少包括如下步骤：A thermal mining method for coalbed methane, at least comprising the following steps:

步骤1、注入：从注入井，向地层注入热能，使煤层加热；Step 1. Injection: inject thermal energy into the formation from the injection well to heat the coal seam;

步骤2、采气：在注入热能的同时，从生产井开采煤层气。Step 2. Gas extraction: coalbed methane is extracted from production wells while injecting thermal energy.

所述的热能种类至少包括：热流体或化学剂氧化生热或电加热的方式之一或其结合。The type of thermal energy includes at least one of heat generation by thermal fluid or chemical agent oxidation or electric heating, or a combination thereof.

当以热流体注入的方式加热时，该开采方法的具体步骤如下：When heating by thermal fluid injection, the specific steps of the mining method are as follows:

步骤a1：从注入井口连续注入热流体，使煤层加热，并驱替煤层气朝生产井前进；Step a1: Continuously inject thermal fluid from the injection wellhead to heat the coal seam and displace the coalbed methane toward the production well;

步骤a2：在注入热流体的同时，从生产井开采煤层气。Step a2: Coalbed methane is extracted from the production well while injecting thermal fluid.

所述的热流体至少为过热蒸汽或热水。The hot fluid is at least superheated steam or hot water.

所述的热流体的注入条件为：The injection condition of described thermal fluid is:

注入温度：注入热流体的温度应当远高于煤层气藏的原始温度，考虑各种热损失后，能使煤层平均温度升高20-60℃以上；Injection temperature: The temperature of the injected thermal fluid should be much higher than the original temperature of the coalbed methane reservoir, and after considering various heat losses, the average temperature of the coal seam can be raised by more than 20-60°C;

注入压力：≤煤层破裂压力；Injection pressure: ≤ coal seam rupture pressure;

注入速度：每米油层：0.01-0.2kg/sInjection speed: oil layer per meter: 0.01-0.2kg/s

所述的热流体的注入总量，根据煤层厚度、煤层孔隙度、开发井组面积确定，当产气井产量低于工业产气量标准时，停止注气。The total injection amount of the hot fluid is determined according to the thickness of the coal seam, the porosity of the coal seam, and the area of the development well group. When the production of the gas production well is lower than the industrial gas production standard, the gas injection is stopped.

当以微波加热方式注入热能时，该开采方法的具体步骤如下：When thermal energy is injected by means of microwave heating, the specific steps of the mining method are as follows:

步骤b1：向装设在注入井内的微波发生器供电，使其向煤层发射用于加热的微波；Step b1: supplying power to the microwave generator installed in the injection well, so that it emits microwaves for heating to the coal seam;

步骤b2：在注入热能的同时，从生产井开采煤层气。Step b2: Coalbed methane is extracted from the production well while injecting thermal energy.

所述的微波加热方式为：由微波发生器直接加热煤层，或由微波发生器对水加热，以加热水产生的热量加热煤层。The microwave heating method is as follows: the coal seam is directly heated by the microwave generator, or the water is heated by the microwave generator, and the coal seam is heated with the heat generated by heating the water.

所述的微波发生器安装在注入井的煤层部位，微波频率为1NHZ-10GHZ，功率为100千瓦-1000千瓦。The microwave generator is installed in the coal seam of the injection well, the microwave frequency is 1NHZ-10GHZ, and the power is 100kW-1000kW.

在注入热能之前，首先自然产气；当日产气量低于工业化开发标准时，再注入热能。Before injecting heat energy, first produce natural gas; when the daily gas production is lower than the industrial development standard, then inject heat energy.

所述的注入井和生产井均至少为一口，且注入井为，注入热量与采气同时在不同的井口进行多于两口时为井组注热力采气。There is at least one injection well and production well, and the injection well is that heat injection and gas production are carried out at different wellheads at the same time, and when more than two well groups inject heat and produce gas.

所述的热能注入量至少使煤层温度升高20℃；且以生产井产气量不低于工业气流为标准。The amount of thermal energy injected can at least increase the temperature of the coal seam by 20°C; and the gas production of the production well is not lower than the industrial gas flow as the standard.

煤层气的热力开采方法，通过向煤层注入热流体(过热蒸汽或热水)或其它增加热能的方法(化学剂氧化生热或电加热)使煤层加热升温。一方面加速解吸，使吸附态甲烷迅速变为游离状态，另一方面热流体在前进过程中驱替游离状态的煤层气朝生产井前进。由于加速了解吸，加上气体的热膨胀，使得生产井产量急剧提高。The thermal mining method of coalbed methane heats up the coalbed by injecting hot fluid (superheated steam or hot water) or other methods of increasing heat energy (oxidation of chemical agents or electric heating) into the coalbed. On the one hand, the desorption is accelerated, so that the adsorbed methane quickly changes to a free state, and on the other hand, the thermal fluid displaces the free state coalbed methane towards the production well during the advancing process. Due to the accelerated desorption, coupled with the thermal expansion of the gas, the production of the production well increases dramatically.

选择注入何种热能，主要根据注入规模、设备费、运行费等因素综合考虑。一般注热蒸汽的投入高，但热量也高，增产效果最好。注热水的设备投资小，但水的热容量也低，增产效果不如注蒸汽。化学氧化剂生热或电加热方法的特点是设备投资小，应用灵活方便，适合于小型气田或井组试验。The choice of what kind of heat energy to inject is mainly based on factors such as injection scale, equipment cost, and operating cost. Generally, the input of hot steam injection is high, but the heat is also high, and the effect of increasing production is the best. The equipment investment for hot water injection is small, but the heat capacity of water is also low, and the effect of increasing production is not as good as that of steam injection. The chemical oxidant heat generation or electric heating method is characterized by low equipment investment, flexible and convenient application, and is suitable for small gas field or well group tests.

注入热流体的温度应当远高于煤层气藏的原始温度，考虑各种热损失后，能使煤层平均温度升高20-60℃以上；注入的压力应尽量高以满足快速注入的需要，但最高不应高于煤层的破裂压力。The temperature of the injected hot fluid should be much higher than the original temperature of the coalbed methane reservoir. After considering various heat losses, the average temperature of the coal seam can be raised by more than 20-60°C; the injection pressure should be as high as possible to meet the needs of rapid injection, but The maximum should not be higher than the fracture pressure of the coal seam.

现场应用时，应根据实际煤层情况，进行经济核算和评价，综合考虑确定各参数。In field application, economic calculation and evaluation should be carried out according to the actual coal seam conditions, and all parameters should be determined comprehensively.

热力驱方式为井组、区块注热流体驱替煤层气的过程。Thermal flooding is a process in which thermal fluid is injected into well groups and blocks to displace coalbed methane.

产气量明显上升为宜。注入量应满足产气速度的要求，一般在生产井产气量下降到低于工业标准时，停止注入。It is advisable to increase the gas production obviously. The injection volume should meet the requirements of the gas production rate. Generally, when the gas production of the production well drops below the industrial standard, the injection is stopped.

本发明具有如下优点：The present invention has the following advantages:

1、加热煤层提高了煤层气(甲烷)的解吸速度；1. Heating the coal seam increases the desorption rate of coalbed methane (methane);

2、温度升高，气体膨胀，提高了渗流速度；2. The temperature rises, the gas expands, and the seepage velocity is increased;

3、热力开采还具有清除井底污染物并疏通堵塞物的作用；3. Thermal mining also has the function of removing pollutants at the bottom of the well and dredging blockages;

4、热力驱可以实现连续、高速开采的目的。4. Thermal drive can achieve the purpose of continuous and high-speed mining.

附图说明Description of drawings

图1为本发明实施例一的示意图；Fig. 1 is the schematic diagram of embodiment one of the present invention;

图2为本发明实施例二的示意图；Fig. 2 is the schematic diagram of the second embodiment of the present invention;

图3为本发明实施例三的示意图。Fig. 3 is a schematic diagram ofEmbodiment 3 of the present invention.

具体实施方式Detailed ways

下面结合附图和具体实施例对本发明的技术方案做进一步说明：The technical scheme of the present invention will be further described below in conjunction with accompanying drawing and specific embodiment:

实施例一：热蒸汽加热开采煤层气Example 1: Exploitation of Coalbed Methane by Hot Steam Heating

如图1所示，设计一注一采两口井，从注入井1的井口连续注入过热蒸汽，注入热流体的温度控制在远高于煤层气藏的原始温度，具体而言，考虑各种热损失后，该温度升高的范围为至少20-60℃以上；注入的压力不大于煤层的破裂压力，并应尽量满足快速注入的需要。蒸汽由注入井1井底进入煤层4后，在煤层4中前进，一方面加热煤层，使煤层的原始温度提高，加速CH4的解吸，使吸附态的甲烷变为游离状态甲烷；另一方面蒸汽在前进过程中驱替游离状态的煤层气向生产井2前进。由于加速了解吸，再加上气体的热膨胀，使得生产井2的产量急剧提高。该方法是连续注入蒸汽，直到生产井2产出大量蒸汽、凝析水，或煤层气日产量低于工业标准时停止注入蒸汽。此时煤层的吸附能力大大降低，解吸速度提高相应提高，生产井的日产量提高因此得到提高，瞬时可增产近千倍。As shown in Fig. 1, two wells, one for injection and one for production, are designed, and superheated steam is continuously injected from the wellhead of injection well 1, and the temperature of the injected hot fluid is controlled to be much higher than the original temperature of the coalbed methane reservoir. After the loss, the range of temperature increase is at least 20-60°C; the injection pressure is not greater than the fracture pressure of the coal seam, and should try to meet the needs of rapid injection. After the steam enters thecoal seam 4 from the bottom of the injection well 1, it advances in thecoal seam 4. On the one hand, it heats the coal seam, increases the original temperature of the coal seam, accelerates the desorption of CH4, and turns the adsorbed methane into free methane; on the other hand, the steam During the advancing process, displace the coalbed methane in the free state to advance toward theproduction well 2 . Due to the accelerated desorption, coupled with the thermal expansion of the gas, the production of theproduction well 2 is dramatically increased. The method is to continuously inject steam until theproduction well 2 produces a large amount of steam and condensed water, or the daily production of coalbed methane is lower than the industrial standard, and the steam injection is stopped. At this time, the adsorption capacity of the coal seam is greatly reduced, and the desorption rate is increased correspondingly, so the daily output of the production well is increased, and the output can be increased by nearly a thousand times in an instant.

实施例二：微波加热煤层开采煤层气Example 2: Microwave Heating Coal Seam Mining Coalbed Methane

如图2所示，设计一注一采两口井，微波发生器3安装在注入井1的煤层4部位，地面工业电源5通过电缆6向微波发生器3供电，微波发生器3发射微波，用微波对地下煤层4直接加热，使煤层4温度升高。微波的频率范围1NHZ-10GHZ之间，微波发生器的功率为100千瓦-1000千瓦，加热后煤层温度达到400℃以上。加热煤层，加速解吸，使吸附态甲烷迅速变为游离状态。由于加速了解吸，加上气体的热膨胀，使得生产井2的产量急剧提高。As shown in Figure 2, two wells are designed, one for injection and one for production. Themicrowave generator 3 is installed in thecoal seam 4 of the injection well 1. The groundindustrial power supply 5 supplies power to themicrowave generator 3 through thecable 6. Themicrowave generator 3 emits microwaves. The microwave directly heats theunderground coal seam 4 to increase the temperature of thecoal seam 4 . The frequency range of the microwave is between 1NHZ-10GHZ, the power of the microwave generator is 100kW-1000kW, and the temperature of the coal seam reaches above 400°C after heating. Heating the coal seam accelerates the desorption, so that the adsorbed methane quickly changes into a free state. Due to the accelerated desorption, coupled with the thermal expansion of the gas, the production of theproduction well 2 is dramatically increased.

实施例三：微波井下锅炉热力开采煤层气Example 3: Thermal mining of coalbed methane with microwave downhole boiler

如图3所示，设计至少一注一采两口井，其中1为注入井，另一口井2为生产井。微波发生器3安装在注入井1的煤层4部位，地面工业电源5通过电缆6向微波发生器供电，由微波发生器发生微波。从地面经油管7向微波发生器注水，微波发生器对水加热成为蒸汽或热水，蒸汽或热水注入煤层。对煤层进行加热。达到提高煤层气产量的目的。As shown in Figure 3, at least two wells, one for injection and one for production, are designed, among which 1 is the injection well and theother well 2 is the production well. Themicrowave generator 3 is installed in thecoal seam 4 of the injection well 1, the groundindustrial power supply 5 supplies power to the microwave generator through thecable 6, and the microwave generator generates microwaves. Water is injected into the microwave generator from the ground through theoil pipe 7, and the microwave generator heats the water to become steam or hot water, and the steam or hot water is injected into the coal seam. The coal seam is heated. To achieve the purpose of increasing the production of coalbed methane.

最后应说明的是：以上实施例仅用以说明本发明的技术方案而非限制，尽管参照较佳实施例对本发明进行了详细说明，本领域的普通技术人员应当理解，可以对本发明的技术方案进行修改或者等同替换，而不脱离本发明技术方案的精神和范围，其均应涵盖在本发明的权利要求范围当中。Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent replacements without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the claims of the present invention.

Claims (10)

1, a kind of heating exploitation method of coal bed gas is characterized in that: comprise the steps: at least

Step 1, injection: from injecting well, inject heat energy, make the coal seam heating to the stratum;

Step 2, gas production: when injecting heat energy, from the producing well exploiting coal bed methane.

2, the heating exploitation method of coal bed gas according to claim 1 is characterized in that: described heat energy kind comprises at least: hot fluid or one of chemical agent oxidative heat generation or electrically heated mode or its combination.

3, the heating exploitation method of coal bed gas according to claim 1 and 2 is characterized in that: when the mode of injecting with hot fluid heated, the concrete steps of this exploitation method were as follows:

Step a1: from injecting the continuous heated fluid injection of well head, make the coal seam heating, and gas displacing coal-bedly advance towards producing well;

Step a2: in heated fluid injection, from the producing well exploiting coal bed methane.

4, the heating exploitation method of coal bed gas according to claim 3, it is characterized in that: described hot fluid is at least superheated steam or hot water; The injection condition of this hot fluid is:

Implantation temperature: the temperature of heated fluid injection should be far above the original temperature of bed gas reservoir, consider various heat waste after, can make coal seam average temperature rising more than 20-60 ℃;

Injection pressure :≤coal seam fracture pressure;

Injection rate: every rice bran oil layer: 0.01-0.2kg/s

5, the heating exploitation method of coal bed gas according to claim 1 and 2 is characterized in that: when injecting heat energy with microwave heating, the concrete steps of this exploitation method are as follows:

Step b1: to being installed in the microwave generator power supply that injects into well, the microwave that makes it be used to heat to the coal seam emission;

Step b2: when injecting heat energy, from the producing well exploiting coal bed methane.

6, the heating exploitation method of coal bed gas according to claim 5, it is characterized in that: described microwave heating is: directly heat the coal seam by microwave generator, or by microwave generator water is heated, with the heat heating coal seam of heating water generates.

7, the heating exploitation method of coal bed gas according to claim 5 is characterized in that: described microwave generator is installed in the position, coal seam of injecting well, and microwave frequency is 1NHZ-10GHZ, and power is 100 kilowatts-1000 kilowatts.

8, the heating exploitation method of coal bed gas according to claim 1 is characterized in that: before injecting heat energy, and at first natural aerogenesis; When the same day, gas production was lower than the industrialized developing standard, heat energy reinjected.

9, the heating exploitation method of coal bed gas according to claim 1, it is characterized in that: described injection well and producing well all are at least flatly, and injecting well is, injecting heat is the gas production of well group heat injection power when different well heads carries out more than two mouthfuls with gas production simultaneously.

10, the heating exploitation method of coal bed gas according to claim 1 is characterized in that: described heat energy injection rate makes the coal seam temperature raise 20 ℃ at least; And being not less than industrial gas with the producing well gas production is standard.

Images