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不外溢”或“水池滲透”,雖然它們不會直接向地表排水,但是蓄水池并不是這些水的終點(diǎn)站,它們會被排放到地面下,一些蓄 水池中滲透量的百分比十分接近一些河流的滲入地下的速率。 另外一種預(yù)測一個(gè)地區(qū)地下煤層中的甲烷量的方法為根據(jù)我們所知道的一些信息,關(guān)于這個(gè)地區(qū)煤層賦存情況和煤層沼氣開發(fā)的可行性,基于這些信息我們進(jìn)行一系列的推算。一 種方法需要估算鉆探到煤層頂部的甲烷貯藏量,然后從煤層中提取中心。 根據(jù)美國地質(zhì)勘測公司的煤據(jù)得到:帕得河水域可重新利用的煤層沼氣變化范圍為 兆立方英尺。水在煤層到井筒移動的過程中使氣體移向井中。在煤層的蓄水層中,提取煤層沼氣的同時(shí)提取出水可以控制煤層氣體的水壓減小。未開發(fā)的煤層沼氣資源存在于懷俄明和曼塔那的帕得河水域,懷俄明的大格林河水域,科羅拉多和新墨西哥的三圈水域。 現(xiàn)在,美國從煤層中獲得的天然氣大約占總的天然氣產(chǎn)出的 7%,羅克山區(qū)估計(jì) 184 兆立方 英尺的天然氣中近三分之一是從席層中獲得的。煤層沼氣是一種類似于甲烷的化合物,它在天然氣中是一種原生能源。煤層沼氣,顧名思義,是在煤層中發(fā)現(xiàn)的,它的生產(chǎn)工藝與傳統(tǒng)的生產(chǎn)方法不同,然而它與傳統(tǒng)天然氣的使用及銷售情況卻是相似的。據(jù)統(tǒng)計(jì)約 24 兆立方英尺的煤層沼氣可能蘊(yùn)藏在曼塔那和懷俄明的帕得河水域。估計(jì)羅克山區(qū)有大約 30— 58 兆立方英尺的可利用煤層沼氣。煤層沼氣的生產(chǎn)中應(yīng)盡量使煤層不要脫水。水壓釋放的同時(shí),氣體上升,并且與水分離從管道中輸送走。懷俄明石油氣體保護(hù)委員會估算,懷俄明地區(qū)帕得河水域可重新利用的煤層沼氣做出估算,結(jié)果大約為 至 兆立方英尺。從煤心中重新獲得的甲烷量,可用來算煤中每單位體積氣體的容量。 對于處理煤層沼氣采出水的現(xiàn)有管理準(zhǔn)則是什么? 現(xiàn)在,在帕得河水域開采煤層沼氣采出的水是通過以下幾種方法處理的: ( 1)排放進(jìn)河道,雖然直接排放到河流存在新的操作法,但是經(jīng)過調(diào)整,還是可以直接排入河流中的。 ( 3)應(yīng)用于農(nóng)作物或牧場,一些水可通過灌溉設(shè)備澆灌農(nóng)田。 為什么人們這樣擔(dān)憂開采煤層沼氣采出水的處理? 有一些關(guān)于煤層沼氣開發(fā)的擔(dān)憂還有怎樣去解決提取早烷所抽出的水。如果按一分鐘 12 加侖來計(jì)算,那么一天從一個(gè)鉆井中產(chǎn)出的總水量大約為 17280 加侖。隨著時(shí)間的推移,煤層沼氣水中的鹽份在土壤深部積累致使鹽的含量對農(nóng)作物產(chǎn)生影響。在有膨脹黏土的濕潤土壤中, 鈉導(dǎo)致粘土的濕潤程度增加,導(dǎo)致粘土微粒的分散和移動。首先,充分的水和時(shí)間在耕種的整個(gè)過程中對土壤的滲透起一個(gè)推動作用。鹽雪松、俄羅斯橄檻等有害物種的侵入被含鹽條件所提高,這個(gè)事實(shí)被很好的證明。然而,如果煤層沼氣水是 陸地供給或流向池塘(那些池塘大部分經(jīng)常不被充填,并且排放到地面下),在開發(fā)過程中由于地下水流向河流,河流流量會增加。 all have varying degrees of accuracy and inaccuracy. According to the U. S. Geological Survey the amount of recoverable CBM from the Powder River Basin ranges from 168。grandathered!177。 therefore, there may be three wells per 80 acres. The quality of CBM product water and its effect on soil: Coal bed methane product water has a moderately high salinity hazard and often a very high sodium hazard based on standards used for irrigation suitability. Irrigation with water of CBM product water quality on range or crop lands should be done with great care and managed closely. With time, salts from the product water can accumulate in the root zone to concentrations which will affect plant growth. Saline conditions stunt plant growth because plants must work harder to extract water from the soil. The sodium hazard of CBM product water poses additional threats to certain soil resources. Sodic irrigation water causes soil crusting and impairs soil hydraulic conductivity affecting water availability and aeration, important to crop growth and yield. Upon wetting soils with swelling clay, sodium causes the degree of swelling in the clay to increase, causing dispersion and migration of clay particles. Current research at Montana State University shows water with sodium levels equal to that in typical CBM product water of Montana can degrade the physical and chemical properties of heavier, clay soils, making such soils pletely unsuitable for plant growth. The risk of sodium has been observed in other soil textures. Jim Oster (personal .) observed crusting, poor soil tilth, hardsetting and aggregate failure on a sandy loam soil irrigated with wat