No 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.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAsphaltene Onset Pressure (AOP) conditions were measured for Kuwaiti Reservoirs fluid samples at reservoir, wellhead, and well-bore temperatures along with the saturation pressures by performing a series of pressure depletion tests using the mercury-free, variable volume, fully visual JEFRI-PVT system with laser light scattering. Asphaltene Deposition Envelope (ADE) and P-T phase diagram were developed. Asphaltene onset conditions were also investigated using different precipitants with Stock Tank Oil (STO). A number of titration experiments were performed on the STO using different alkanes and CO 2 . Our investigation has revealed that CO 2 is the most effective asphaltene precipitant followed by alkanes (C 1 to C 7 ). To investigate the molecular structure of the asphaltene molecule, advanced analytical techniques such as 1 H and 13 C NMR and IR spectrometers have been utilized. It was concluded that the total number of carbon atoms was 220 of which 120 were associated with aromatic and the rest were aliphatic rings. The number of aromatic and naphthenic rings were estimated to be 42 and 114 rings respectively.

Currently Kuwait Oil Company (KOC) is facing asphaltene deposition problems in the wellbore of some of the Marrat Jurassic reservoirs in West Kuwait (WK) and South East Kuwait (SEK). 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. This paper describes the results of the laboratory studies on the characterization and phase behavior studies of three different crude oil samples from Marrat reservoirs, and the screening of a number of commercially available inhibitors, which were proposed as a remedy and prevention of asphaltene deposition for this reservoir. Initially the samples were characterized for their chemical and physical properties. Then the phase diagram (P-T) and Asphaltene Deposition Envelope (ADE) for bottom-hole samples were established by measuring the saturation and Asphaltene Onset Pressures (AOP) at different temperatures from reservoir to surface conditions by using the laser technique Solid Detection System (SDS). Asphaltene Flock Point (AFP) analyses were then performed by the titration technique using Stock Tank Oil (STO) samples and n-Heptane as the asphaltene precipitant. The effects of different concentrations of each inhibitor on different reservoir fluids were investigated in the laboratory, using the AFP technique. The most efficient inhibitor with the optimized concentrations for each reservoir fluid was established for economical evaluation purposes. Based on these studies, a selected inhibitor is now being used for a pilot field study. Introduction Asphaltene precipitation and deposition from oil reservoir fluids during production is a serious problem as it can cause plugging of reservoir formation, wellbore, tubing and production facilities.

The increasing amount of oil field waste is a matter of concern. This study proposes the Slurry Fracture Injection (SFI) technique as an alternative waste disposal method. The proposed waste disposal method is complete and leaves few future liabilities. The entire waste can be injected into an isolated deep geologic zone with no contamination of water-bearing formations or formations outside the targeted zone. The method can lead to the reclamation of oil industry landfills and the oil pits and dumps. We propose a two-tiered screening method for evaluating the feasibility of this technology and identification of a suitable target zone. A stringent environmental monitoring program should complement the SFI process to ensure environmental compatibility.