Reservoir management engineers at Aramco are fortunate to have a wealth of information about their reservoirs in the corporate database. However, this wealth of information comes with a challenge of analyzing this immense collection of data and utilizing this information for decision-making. In this study we used data mining process to explore our database and evaluate the performance of wells in a study area of Ghawar field. The performance of more than 450 wells was then related to the super-k existence from flowmeter data. The existence of super-k layer was believed to cause premature water breakthrough and hence poor vertical sweep. The objective of the study was to answer the following question: Will producing a super-k well without isolating the super-k layer result in less cumulative oil production after water breakthrough? In this paper we developed a methodology to identify and quantify super-k while avoiding the pitfall of black or white (i.e. super-k or non super-k well). Super-k quantification was accomplished by deriving Fluid Flow Index from flowmeter surveys. The next challenge was to come up with a consistence measure of well performance so that all the wells can be compared on the same basis. This challenge was overcome by introducing the new definition of cumulative oil production and average oil rate after water breakthrough. In this paper we developed correlations to predict the performance of future wells to be drilled in the area. The study indicated that there was a positive correlation between super-k and high average rate after water breakthrough. Also, it was found that anomalous flood front encroachment in the east flank of the field is unrelated to the super-k. The study showed that reservoir performance is controlled by the interaction between Faults/ Fractures and Super-k layers. The results of this study created a paradigm shift in perceiving super-k layers in Ghawar. Field data showed an improved well performance by perforating isolated super-k layers. Moreover, the derived Fluid Flow index was used in building an enhanced and more realistic model for the field. Introduction Super-K or extremely permeable intervals are quite common in the study area of Ghawar field. In this carbonate reservoir, super-k zones can be horizontal layers, created during deposition or after digenesis, or they are just as likely to be sub-vertical fractures and faults1. However, since most of the wells in the study area are vertical, the probability of intersecting sub-vertical fractures and faults is very low. The first approach to treating super-k zones in carbonate reservoirs is to identify the nature of these zones in the wellbore. To this end, flowmeter logs is required to first identify potential zones and second characterize their properties. Continuous flow meters are routinely obtained in wells with openhole completions in Ghawar field to improve sweep from all the zones. It became apparent that in some wells, extremely high fluid-flow was confined to thin, apparently strati-bound ‘super-permeable’ intervals. This is in marked contrast with other wells, where continuous flow meters indicated that the fluid flow was distributed more uniformly across the openhole reservoir section.

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Logging through casing is an important measurement for reservoir surveillance in mature fields. In the last 70 years, thousands of producers have been drilled in Y field, Saudi Arabia, and many are producing water.Successfully identifying by-passed oil and monitoring oil/water movements are critical for successful management of the Y field.In this study, cased-hole formation resistivity (CHFR * ) was field tested and evaluated in two wells in the Y field and in a third well in Z field. The three tests cover the following conditions; carbonate and shaly sand reservoirs, vertical and horizontal wells, and oil producing and water injection wells. In general, the CHFR measurements agree well with the openhole wireline and LWD logs. In low and high resistivity reservoir intervals, differences were observed. To address these differences, CHFR theory is reviewed and application conditions of CHFR logging are discussed. Guidelines for future CHFR jobs are presented. Run in small tubing Need slim tool Washed-out holes DOI Flowing wells Hold-up Fluid contacts in hole C/O analysis Near wellbore effects DOI Deviated wells Acid effect High Σ LithologyThe main applications of CHFR are: (1) to re-evaluate existing fields by locating by-passed hydrocarbon, (2) to monitor movement of gas/oil, gas/water, or oil/water contacts, (3) to monitor reservoir saturation changes with time, and (4) to provide resistivity log in difficult-to-drill wells where openhole log is not available.To introduce a new tool such as CHFR into Saudi Arabia, however, extensive field tests and evaluation are normally required. This report summarizes the CHFR test results in Y field and an application example in Z field, including: (1) test of CHFR in a carbonate oil reservoir in well Y-472, (2) test of CHFR in the carbonate oil reservoir swept by injected water in well Y-457, and (3) application of CHFR in well Z-321 where more than 1000' of LWD resistivity and gamma ray data in a shaly sandstone oil reservoir was lost due to LWD tool malfunction. # Color code in Table 1: Black -not recommended. Grey -use with caution.White -recommended. Csalt -concentration of salt (salinity). DOI -depth of investigation. In many situations, the tool measurements are complementary.

Summary In this paper, we present a novel method for in situ estimation of two-phase transport properties of porous media using time-lapse resistivity, pressure, and flow rate data from permanent downhole pressure, electrode resistivity array (ERA), and production logging tools. The objective of this fluid movement monitoring (FMM) experiment is to develop a new downhole hardware assembly, new measurement procedures, and associated interpretation techniques for inferring oil recovery factor, relative permeabilities to oil and water, and other two-phase flow properties. An oil well in a carbonate reservoir in Saudi Arabia was dedicated to conduct a week long extensive openhole monitoring data acquisition, enabling us to carry out suitable a priori characterization. This approach is new to the oil industry and is the first field experiment for direct determination of two-phase flow properties through successful integration of the downhole resistivity array and pressure data. Together with pressure transient responses, the ERA measurements allowed characterization to a radial distance of tens of meters from the wellbore.

TX 75083-3836, U.S.A., fax 01-972-952-9435. Abstract:This paper discusses the assessment of Residual Oil Saturation (ROS) in a large, prolific, water flood carbonate Arab-D reservoir in the Middle East. The determination of Residual Oil Saturation is very important since it is a crucial step in the accurate evaluation of sweep efficiency, reservoir management strategy, EOR feasibility, and oil recovery factors. Recovery in a water flood reservoir is the function of economic limit, and displacement and sweep efficiency (in both areal and vertical direction).