Production history matching to determine reservoir properties of important coal groups in the Upper Pottsville formation, Brookwood and Oak Grove fields, Black Warrior Basin, Alabama
Production history matching to determine reservoir properties of important coal groups in the Upper Pottsville formation, Brookwood and Oak Grove fields, Black Warrior Basin, Alabama
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DOI：
10.1016/j.jngse.2012.10.005
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发表时间：
2013-01-01
影响因子：
--
通讯作者：
Karacan, C. Oezgen
中科院分区：
文献类型：
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作者：
Karacan, C. Oezgen
亚拉巴马州的黑武士盆地是美国最重要的煤炭开采和煤层气生产区之一。大约25年前，为了确保采矿安全，开始了通过脱气进行甲烷控制的努力，导致5000多口煤层气威尔斯井分布在整个盆地的各个领域。这些威尔斯井主要在上波茨维尔地层的普拉特、玛丽李和黑溪煤组中完成，并提供了一个了解这些煤的甲烷储层特性和改善其脱气性能的独特机会。由于目前的长壁采煤活动，黑勇士盆地的布鲁克伍德和橡树格罗夫油田可能是该盆地最重要的两个油田。在这项工作中，甲烷和水的生产92垂直钻井，一些完成20年前，在目前的大型煤矿区位于这两个领域，通过历史拟合技术进行了分析。这些钻孔是在玛丽李煤矿群或普拉特、玛丽李和黑溪煤矿群的组合中完成的。根据各组煤的性质建立历史拟合模型，递减曲线分析表明，威尔斯井的有效指数递减率在2%~ 25%之间。生产历史匹配的结果表明，虽然它们因煤类而异，但在某些地区压力下降高达80%，接近25 psi，并导致甲烷含量相应下降。煤中的含水饱和度从100%降低到20 - 80%，气体相对渗透率提高到0.8。由于一次贫化，煤层的渗透率增加了10和40%之间的原始渗透率，这取决于深度和煤层1和10 MD之间的变化。这些结果不仅可以用于诊断和解释的目的，但可以用作概率模拟中的参数分布，如本文的最后一节所示。它们还可以与空间建模和地质因素结合使用，以计算运营矿山的潜在甲烷排放量。由爱思唯尔公司出版
The Black Warrior Basin of Alabama is one of the most important coal mining and coalbed methane production areas in the United States. Methane control efforts through degasification that started almost 25 years ago for the sole purpose of ensuring mining safety resulted in more than 5000 coalbed methane wells distributed within various fields throughout the basin. The wells are completed mostly in the Pratt, Mary Lee, and Black Creek coal groups of the Upper Pottsville formation and present a unique opportunity to understand methane reservoir properties of these coals and to improve their degasification performances.The Brookwood and Oak Grove fields in the Black Warrior Basin are probably two of the most important fields in the basin due to current Iongwall coal mining activities. In this work, methane and water productions of 92 vertical wellbores drilled, some completed 20 years ago, over a current large coal mine district located in these two fields, were analyzed by history matching techniques. The boreholes were completed at the Mary Lee coal group, or at combinations of the Pratt, Mary Lee, and Black Creek groups. History matching models were prepared and performed according to properties of each coal group.Decline curve analyses showed that effective exponential decline rates of the wells were between 2% and 25% per year. Results of production history matching showed, although they varied by coal group, that pressure decreased as much as 80% to nearly 25 psi in some areas and resulted in corresponding decreases in methane content. Water saturation in coals decreased from 100% to between 20 and 80%, improving gas relative permeabilities to as much as 0.8. As a result of primary depletion, permeability of coal seams increased between 10 and 40% compared to their original permeability, which varied between 1 and 10 md depending on depth and coal seam. These results not only can be used for diagnostic and interpretation purposes, but can be used as parameter distributions in probabilistic simulations, as illustrated in the last section of this paper. They can also be used in conjunction with spatial modeling and geological considerations to calculate potential methane emissions in operating mines. Published by Elsevier B.V.