Decline Curve Analysis in The Upper Kais and Middle Kais Layers, Kais Formation, “W” Field, West Papua

Abstract

The "W" Field is an old oil field located in onshore of the Bintuni Basin, West Papua. The field was discovered by Nederlandsche Nieuw Guinee Petroleum Maatschappij (NNGPM) in 1941 and cumulative production are 2.1 MMBBL. The reservoirs were  recognised as generally tight with fractures necessary for significant oil production from Limestones of Kais Formation. The field has 30 wells (12 production wells), which were produced in 1952-1961. The "W" field is devided into Compartment 1 (penetrates Upper Kais Layer) and Compartment 2 (penetrates Upper and Middle Kais Layer) by sealing faults. This study aims to determine the productive layers age, Estimate Ultimate Recovery (EUR), Recovery Factor (RF) and Estimate Remaining Reserves (ERR) in each layer and compartment. This research method first, calculates economic limit, secondly, observes a decrease in production curve and chooses a trend to calculate Decline Curve Analysis with loss ratio and trial error and x chi square test methods. Next, choose the price of b and the corresponding terms, which are used to forecast reserves. The research results are obtained as follows; Decline Curve analysis on "W" Field Compartment 1 Upper Kais Layer with ERR of 4123.648 STB, obtained production age of 11.292 months, EUR of 306901 STB and RF of 6.936%, 2 in Compartment 2 Upper Kais Layer with ERR of 24974.632 STB , obtained production age of 26.072 months, EUR of 434435.3647 STB and RF of 1.850%, in Compartment 2 Layer of Middle Kais with ERR of 3014779.202 STB, obtained production age of 1514.532 months, EUR of 4069146.767 STB and RF of 18.553%.