利用物質平衡機率統計法評估台灣海域凝結油氣田資源量

油氣田探勘初期，通常使用體積機率法進行油氣資源量評估。通常所需參數為油氣層面積、厚度、孔隙率、原生水飽和度、地層體積因子及採收率，但在探勘初期因相關資料不足，導致資源量估算結果不確定性高，而且並無考慮採收率與油氣田原始埋藏量間的相關性以及受水驅(water drive)之影響，因此造成許多不必要的誤差。本研究結合物質平衡法與體積機率法，在水驅模式下，探討影響油氣層採收率的相關因子，並利用線性多項式描述油氣田資源量與影響因子之相關性，根據此多項式配合機率統計法估算資源量，本研究針對台灣海域凝結油氣田，評估該油氣田可採資源量(resource)，並與傳統體積機率法之結果相比較。由結果顯示，此凝結油氣田之採收率與原始埋藏量呈正相關，此相關性在利用體積機率法估算時通常被忽略，故利用傳統體積機率法評估資源量時會產生較大的誤差。根據本研究所建立之方法估算資源量時，可避免由參數相關性所產生之誤差，提高資源量評估之準確度，降低不確定性，該凝結油氣田在氣相資源量之中間值為332 mmscm；油相資源量之中間值為1.261E+05 Kl。本研究根據一個真實的案例可發現一無因次的線性關係式，所建立之方法不僅保有體積法之快速評估資源量之優點，亦可降低油氣評估時的不確定性，減少探勘的風險。日後應用在不同油氣田時，只需篩選其資源量之影響因子，找出其線性關係式之相關係數，即可進行資源量評估。

關鍵字

油氣埋藏量；資源量；體積機率法；物質平衡法；水驅；氣層

並列摘要

Volumetric with probability method is a general one applied for the evaluation of resource during the exploration period. Several factors, such as formation area, payzone thickness, connate water saturation, formation volume factor, are required for the calculation. Lacking of detailed reservoir information, the estimation results, in general, are usually with high uncertainty. Neither water drive nor the inplace volume effects on the recovery factor are considered. To reduce the above mentioned uncertainty, a combination workflow for both material balance (MBAL) and volumetric probability is used to calculate the reserve. A sensitivity study was first performed by MBAL to find the important factors, which affect the recovery factor. A linear correlation was found to describe effects on the recovery factor with consideration of inplace volume, water permeability, water radius to gas radius ratio, water to gas ratio on recovery factor. Based on this correlation, volumetric with probability method is then used to estimate reserve. In this research, we applied the combination method for an offshore gas condensate reservoir for the calculation of resource. Resource of gas is 332 mmscm and oil is 126,100 kl for P50. Comparing our results with volumetric one, it is shown that combination method is not only reduces the calculation uncertainty as expected but did not need a long time to perform the whole process. A dimensionless linear correlation can be found in a real case. A positive correlation between original inplace and recovery was found as well and is usually ignored while calculating resource by volumetric method. In summary, a quick and more accuracy workflow was developed by this research for the application for reserve estimation during exploration period. This workflow can be applied to other field after screen the sensitive factors and find the new linear correlation’s constants.

並列關鍵字

OOIP ； OGIP ； resources ； volumetric ； material balance ； water drive ； gas reservoir

參考文獻

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[7] 曾繼忠、吳偉智、黃瑞鴻、陳大麟，「台灣北部某氣層原始氣體埋藏量探討」，礦冶，2001，第173期，105-112頁。

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利用物質平衡機率統計法評估台灣海域凝結油氣田資源量

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