EMULSIFIED FLUID IN ACID FRACTURING TREATMENT INCREASES PRODUCTION OF BERINGIN WELL

摘要

Pertamina as the national oil company has assets that need production optimization to increase reserves recovery. Production targets have been continuously increasing but the production needs some efforts to be maintained and achieve those targets. Most of the recoverable reserves are still underground and need to be produced in an optimum way. Pertamina Sumatera produced its first oil in Beringin Field in 1975 (Figure 1). Current production is not only from oil but also gas production. The demands from government have pushed the gas production optimization. Beringin Field is one the largest contributing fields for South Sumatera operations.It is not uncommon that suspended wells are reactivated after long time. One of the challenges for well's reactivation is to achieve an economical production rate after intervention. Some of the contributing factors are skin build up, reservoir pressure depletion; water production, facility and lifting optimization operation.Fracturing was intended to stimulate the Beringin well and put the well back on production econom-cally. Considering its clean mineralogy, acid soluble lithology, medium permeability and unknown damage penetration; acid fracturing was selected as the best and most efficient stimulation technique to be applied. The highly conductive fracture also enables the zone to be produced economically at a lower drawdown, improving productivity and ultimate recovery from the well.Acid fracture treatment was performed with emulsified acid which has the advantage of retarding the reaction thus helping to get fracture length especially in this high bottomhole temperature environment. The acid fracturing design used a specific technique consisting of alternating stages of a non reactive pad fluid with stages of retarded main acid system.This technique provides an effective method of fluid leak off control during an acid fracturing treatment. This helps to keep the acid in the main fracture, enabling the creation of longer etched fracture half length and additional wormholes farther from the wellbore.The fracture geometry from simulator showed frac length of 132 ft and width of 0.252 inch and conductivity of 37721 md.ft. The very promising result has been observed after fracture stimulation treatment. The well was producing at stable rate for more than one year.The fluid selection pumping methodology and an adequate fluid volume are the most contributing factors for this promising production result.