Laboratory Investigation of Asphaltene Precipitation problems during CO2/Hydrocarbon Injection Project for EOR Application in Kuwaiti Reservoirs

Oskui, Gholam-Reza Poshtchi (Kuwait Institute for Scientific Research) | Jumaa, M.A. (KISR) | Abuhained, Waleed

OnePetro 

Abstract
Asphaltene precipitation and deposition from oil reservoir fluids during production are serious problems for the oil industry, as it can cause plugging of reservoir formation, wellbore, tubing and production facilities. Kuwait Oil Company (KOC) is facing asphaltene deposition problems in the wellbore of some of the Marrat Jurassic reservoirs in West Kuwait (WK), South East Kuwait (SEK) and North Kuwait (NK). This has caused a reduction in production and shutting of some of the wells and a severe detrimental effect on the economics of oil recovery.

As part of a major strategic program for development of the master plan for Improved and Enhanced Oil Recovery (IOR/EOR) techniques for Kuwaiti reservoirs, two projects have been conducted by a joint team in Kuwait Institute for Scientific Research (KISR) and KOC to screen all the reservoirs with the available techniques by assessing incremental recovery. Miscible gas injection such as CO2 and Hydrocarbon techniques were recommended for more than 80% of the
light oil reservoir in Kuwait. Currently the Field development (FD) teams in KOC are planning further investigation and are conducting lab tests and simulation
studies to design the first pilot tests for CO2/HC injection for several of the selected reservoirs in NK, WK. Comprehensive laboratory testing, modeling
tuning and simulation preparation is required for this design study.

Any Oil production processes and the application of IOR & EOR can modify the flow and phase behavior of the reservoir fluids, and rock properties. These modifications could lead to asphaltene precipitation. Asphaltene deposition on formation is a serious problem, and it might occur during CO2/gas injection, and can cause porosity and permeability reduction in the reservoir, and plugging wellbore and piping in production facilities. In the planning of any gas injection IOR projects, the flocculation and deposition of asphaltene in porous media and their interaction with rock and fluid represent complex phenomena which need to be investigated under dynamic flowing conditions.

In this paper, a systematic approach for the investigation of Asphaltene problems in reservoirs during primary production, pressure depletion and IOR/EOR processes under gas injection processed will be presented. Some of the results of the initial laboratory studies on the characterization and phase behavior studies of typical crude oil samples from Kuwaiti reservoirs will be presented.

Introduction
As the end of the era of easy oil production is approaching, various IOR/EOR technologies will be applied to matured reservoirs worldwide. Using these technologies, 60 % or more of the reservoir's original oil in place can be extracted, compared with only 20-40 % using primary and secondary recovery.
CO2 gas injection, chemical injections and thermal recovery techniques are the main approved technologies that are being applied in future developments during both secondary and tertiary stages of oil recovery. CO2 injection from industrial plants emission also provides another beneficial opportunity due to the added value of dealing with global warming and reducing Green House Gas (GHG) emission by CO2 sequestration and as storage oil/gas reservoirs.