The distribution of natural nuclide gamma-ray activities and their respective annual effective dose rates, produced by potassium-40 (⁴⁰K), uranium-238 (²³⁸U), thorium-232 (²³²Th), and radium-226 (²²⁶Ra), were determined for 14 oilfield scale samples from the Middle East. Accumulated radioactive materials concentrate in tubing and surface equipment, and workers at equipment-cleaning facilities and naturally occurring radioactive materials (NORMs) disposal facilities are the population most at risk for exposure to NORM radiation. Gamma-spectra analysis indicated that photo-gamma lines represent the parents of 10 radioactive nuclides: ²³⁴Th, plutonium-239, actinium-228, ²²⁶Ra, lead-212 (²¹²Pb), ²¹⁴Pb, thallium-238 (²⁰⁸Tl), bismuth-212 (²¹²Bi), ²¹⁴Bi, and ⁴⁰K. These nuclides represent the daughters of the natural radioactive series ²³⁸U and ²³²Th with ⁴⁰K as well. The mean activity concentration of ²³⁸U, ²³²Th, and ⁴⁰K were found to be 25.8 ± 11.6, 18.3 ± 8.1, and 4487.2 ± 2.5% Bq kg⁻¹ (average values for 14 samples), respectively. The annual effective dose rates and the absorbed doses in air, both indoor and outdoor, for the samples were obtained as well. The results can be used to assess the respective hazard on workers in the field and represent a basis for revisiting current engineering practices.

Performing look back studies to evaluate the economic and technical impacts of filed management decisions, is not a common occurrence in our industry. Even when such studies are performed, the results are hardly ever published for evaluation and scrutiny by the larger community of industry professionals. This paper presents such a study in the case of a mature giant oil field in the Middle East.This prolific mature asset that includes more than 160 production wells has been the subject of peripheral water injection for many years to maintain pressure and help displace oil toward the production wells. Production was restricted to 1,500 bbls of fluid per day per well to avoid excessive water production as well as pulling oil from an over produced overlaying prolific reservoir. In 2005 a reservoir management study was commissioned to evaluate the impact of rate relaxation in this asset. The objective was to explore the likelihood of increasing oil production from the asset while minimizing the possibility of increasing the water cut.The study was performed using the existing, history matched reservoir simulation model. To maximize the utility of the numerical model an AI-Based proxy model called Surrogate Reservoir Model (SRM) was developed and used for the study. Upon completion of the study (during the second quarter of 2005) the SRM ranked all the wells based on the probability of success 1 , once the rate relaxation program is implemented. In January 2006, management issued permission for the rates in 20 wells to be relaxed.Using actual field data, this paper reports and evaluates the results and the consequences of the field management decisions, more than five years after their implementation. The approach and methodology used in this project will help reservoir and production managers, engineers and modelers make the most of the tools that are at their disposal to make more informed field management decisions. This paper demonstrates that using the right tools and strategies, skepticism about reservoir simulation models can be addressed effectively and can result in highly successful practices.

Reservoir management requires tools that can (a) provide fast track and accurate assessment of a large variety of operations, while (b) are capable of quantifying uncertainties associated with management decisions. Reservoir managers must be able to compare and contrast a large number of development scenarios, while taking into account the uncertainties and risks involved with each scenario, in a relatively short period of time. To achieving this important task with traditional technologies one must either sacrifice the accuracy or the speed.