Abstract:

Abstract: The fracturedvuggy reservoirs in Tahe Oilfield are characterized by strong heterogeneity in spatial distribution, size, and quality of reservoirs, thus their proven reserves calculated with method formulated for clastic reservoirs are inaccurate. Therefore, their proven reserves are classified and evaluated based on the seismic reflectance signature, rate of seismic amplitude variation and difference of the measured deliverability among wells. Undeveloped reserves are divided into proved underdeveloped reserves, unevaluated Class Ⅰ reserves, unevaluated Class Ⅱ reserves, and reserves to be cancelled after verification. Various approaches are introduced for defining boundaries of reserves of different categories. As each approach has its only limitations, it is necessary to integrate multiple methods for evaluating reserves. These classification and evaluation approaches are used in the fracturedvuggy carbonate reservoirs in Tahe oilfield. The results show that they can effectively guide the emplacement of development wells, give priority to the producing of high quality reserves, strengthen evaluation of the unevaluated Class I reserves, enhance singlewell deliverability and ratio of producing reserves.