Investigation on the performance between water alternating gas and water huff n puff techniques in the tight oil reservoir by three-dimensional model simulation: A case study of Jilin tight oil field

Abstract

Oil production in most of the old reservoirs is expected to decline, and this will create a gap between the supply and demand of oil in the world. Meanwhile, there are still huge volumes of hydrocarbons in unconventional reservoirs. Intensive technological approaches are needed to ensure adequate oil is recovered than developing other new fields, which are more expensive economically. Therefore, there is a rising interest in developing effective, improved oil recovery techniques to increase oil recovery from depleted oil fields or unconventional oil resources. This study mainly intends to compare the Water Alternate Gas (WAG) and the Water Huff n Puff techniques for oil recovery in a tight oil reservoir, based on their effectiveness, their recoveries, and economical factors, as well as assessing the factors that affect the recovery based on both of the techniques. The modeling and designing of the reservoir for the Jilin tight oil field and its simulation were carried out by the ECLIPSE 300 software. The result showed that, after a simulation of 2922 days, Water Alternating Gas (WAG) has better results than using a Water Huff and Puff by providing a total of 30,453.271 Sm of the total field oil and the Water Huff and Puff method has a total field oil production of 1,726.389 Sm3. Besides good oil recovery, the WAG method has shown higher water production compared to that of water huff and puff, with 46157.715 Sm3, while the water huff and puff have only produced total field water of 138.874 Sm3 for the whole 2922 days of simulation. Furthermore, the WAG best mode, which shows an optimum oil recovery efficiency of 47.40 %, is an injection mode by starting with water injection followed by gas injection (CO2) for1-year cycle each. Thus, WAG is a preferential candidate for the development of tight oil reservoirs.