煤層氣可採蘊藏量新評估法研究

A Novel Method of Reserve Estimation for Coalbed Methane

曹繼忠(Chi-Chung Tseng) ； 吳柏裕(Po-Yu Wu) ； 陳大麟(Ta-Lin Chen) ； 林再興(Zsay-Shing Lin)

《臺灣鑛業》 63卷3期 (2011/09) Pp. 1-17

https://doi.org/10.30014/TMI.201109.0002

摘要

由於傳統石油及天然氣資源逐漸減少，石油業界已開始著手非傳統油氣資源之探勘及開發生產，煤層甲烷氣便是非傳統天然氣資源之一。在評估煤層氣礦區時，首要的工作是估算其蘊藏量或資源量，但由於煤層氣的氣層性質比傳統天然氣層的性質複雜很多，採體積法進行估算時，雖然所需參數極少，但採收率不易準確估算，往往過於樂觀；若採油氣層模擬方法，則必須對目標礦區掌握較正確之地質模式才能正確地評估，此在探勘階段又不易達成。因此，本研究的主要目的是針對煤層氣最常見的生產井配置模式，發展出一套探勘階段煤層氣蘊藏量的新評估方法，利用煤層氣模擬技術，結合數值迴歸方法，獲得煤層氣採收率之關係式，以利探勘階段工程人員不需使用複雜的模擬軟體便可快速且較準確地評估煤層氣之蘊藏量或資源量，並作為經濟分析及投資決策之用。本研究以國外探勘階段煤層氣礦區評估資料作為虛擬案例，應用新評估法進行礦區評估，評估結果證明該方法除了可快速提供煤層氣礦區鑽井數與單井掃排面積之敏感度分析外，亦可提供初步之經濟分析之用，且其結果與模擬所產生之結果並無太大差異。由於所建立的新方法為單純之數學關係式，尚可結合統計軟體（如Crystal ball），進一步以機率法評估煤層氣之P10、P50 及P90 蘊藏量，對評估探勘階段礦區而言，較易解決地質參數之不確定性問題。此外，本方法同樣亦可應用於台灣煤層氣礦區，快速評估台灣煤層氣開採之可行性。

關鍵字

原始氣體埋藏量 ； 煤層甲烷氣 ； 油氣層模擬 ； 採收率

並列摘要

The oil industries start working with exploration and development of unconventional resource due to the decreasing of conventional oil and gas resources. Coalbed methane (CBM) is one of unconventional natural gas resources. Reserve or resource estimation is the principal work of CBM evaluation. The volumetric method often used in conventional gas was prone to be too optimistic in coalbed methane reserve estimation since the properties of CBM are more complicated than conventional gas and the recovery factor is difficult to decide accurately. Reservoir simulation needs an accurate geological model, which is difficult to acquire in exploration phase. A CBM reserve estimation method in exploration phase was developed in this study for the most common CBM production wells pattern.A CBM recovery factor correlation was developed with reservoir simulation and numerical regression. Engineer may quickly and accurately appraise the CBM reserve or resource for the purposes of economic analysis and investment decision-making in exploration phase without using complex simulation software. An exploration phase CBM case was evaluated with this new assessment method. The evaluation results demonstrate that the method can quickly provide the sensitivity analysis of well spacing or well number, it can also provide a preliminary economic analysis and its results is not much different with simulation result. Since the new method is a simple mathematical correlation, it can be combined with statistical software (such as Crystal ball) for further evaluation of P10, P50 and P90's reserves with probability method. It is relatively easy to solve the uncertainty problem of geological parameters in exploration phase. In addition, our results can also quickly apply in Taiwan for the feasibility study of CBM assessment.

並列關鍵字

Original gas in place ； CBM (Coal Bed Methane) ； Reservoir simulation ； Recovery factor