Unwanted water production is a major challenge in the horizontal wells in the Greater Burgan field in Kuwait. The long lateral sections and the presence of heterogeneity lead to uneven sweep of hydrocarbons. Greater Burgan has over 60 horizontal wells to date. Initially they produced dry oil and up to the expectation but soon the water cut increased in a number of wells and avoiding water break through became a major challenge. Burgan sandstone is a highly productive reservoir and the permeability variation is huge from less than a Darcy to a few Darcy. Thus, the horizontal wells have uneven flow profile and subsequent coning and cresting effects resulting in bypassed oil and poor recovery. To have a better down-hole water management in horizontal wells a number of options from chemical water shut-off and isolating the toe side using packers to use of straddle packers in the middle and heel side of the horizontal section were tried. However, the use of Inflow Control Device-ICD proved to be the best option to restrict and slow down and contain the water production by creating additional pressure drop and achieve better sweep efficiency. The first ICD completion in the Greater Burgan field and in KOC was implemented in a sidetrack well in 2007. To date the well is flowing with 45% water cut which is almost constant from the beginning for 7 years now. It resulted in a net gain of 2400BOPD from this well. This paper will describe this case history, how the system was designed, completed, and monitored, and the successful results achieved for over 7 years. This successful use of ICDs for water conformance lead to more applications in Kuwait and will give a good understanding for the future use in other areas.

This Pawr was selected for presentation by an SPE Prwram Committee following review of information containad m an abstract submittad by the author(s). Contents of the paper, as presented, have not been retiewed by the =ety of Petroleum Eng,neers and are subject to correction by the author(s). The material, aa presented, does not necessarily reflect anỹ itlon of the Society of Petroleum Engmeera, Its o~cera, w members. Papers presented at SPE meetings are subject 10 pub~cafion mtiew by Editorial Committees of the Society of Petroleum Engineers. Electronic reproduction, distribution, or storage of any part of this paper for mmmetial Purpmaa without the~tten consent of the *lety of Petroleum Engineers is prohibited. Permission to reproduce In print is restnctad to an abstract of not more than 300 tis; hllustratlons may not be copied. The abslract must contain mnspicuous acknowledgment of Mere and by tiom the papr was presented. Write Librarian, SPE, PO. Sax 833836, Richardson, TX 75083-3836, U. S.A., fax Ot -972-952-9435. AbstractIn fluvially dominated delta plain reservoirs, such as the Wara formation in the Greater Burgan Field, characterizing a reservoir's flow properties accurately is essential in developing a sound reservoir model. This is easier said than done. Typically, lithofacies identified in cores are correlated to multiple log suite characteristics. These are then used to help define simulation flow properties in wells. In Greater Burgan, with over fif~years of production, much of the field development occurred before modem diagnostic logging tools became available. Therefore, direct correlation of core lithologies and corresponding lithofacies description to multilog character is not possible in the majority of wells.Relationships discovered between shale volume (V~H) ranges and effective porosity (~to permeability transforms allowed us to apply unique rock properties to flow units or "facies" de fried by the V~H-porosity ranges. These flow facies eliminated the difficult task of trying to predict changing lithologies and lithofacies in wells with limited log traces and no core.

In the recent past four shallow wells were drilled in the Ahmadi Area and the purpose of these wells was to observe the fluid movement in these wells, either to the surface or communication between the zones in the down-hole. These unconventional wells were designed for unrestricted inflow of fluids into the wellbore as appreciable commercial flow was never expected. The challenge was also to log the flow and pinpoint the fluid entry points. Conventional PLT tools were not suitable as spinners threshold velocity could not be achieved in such feeble flow. Research was done to find the most suitable tools and equipment that are available in the industry and most useful to this project at very shallow depths and in real-time monitoring. It was decided that the minor temperature variation against the contributing zone could be captured real-time by DTS (Distributed Temperature Sensors) and Permanent Down-hole Gauges will give the real-time pressure and temperature readings at the point of its installation in the wellbore. These data can be analyzed to quantify the flow contribution and fluids entry points. At this shallow depth the effect of diurnal temperature change was also a main factor. The DTS and Permanent Down-hole Gauges were installed in all 4 wells, 3 of these are 250’ deep and the fourth well is 1000’ in depth. The performance of these tools gave very distinctive results that benefitted in the investigation of the fluid movement in these wells and in the surrounding. This paper and presentation will show the details of this project for the 4 wells and the installation and performance of these tools and how it benefitted the project. The real-time monitoring of these data and the challenges encountered will also shared.

The Mauddud Formation in the Greater Burgan field is a thin carbonate reservoir with very low permeability but with moderate to good porosity and variable fracture density. The formation could be divided into three distinctive layers, based on the structural and digenetic complexities. Production in Mauddud wells show rapid decline due to tight rock matrix (low permeability). This decline is associated with an increase in Gas-Oil Ratio (GOR) as reservoir pressure falls below the bubble point pressure near the wellbore. Horizontal wells were drilled in an attempt to develop the Mauddud Formation targeting sweet zone. Most of the wells were located in a relative structural high on the up-thrown blocks of the North and Eastern flank of the Greater Burgan field that had the highest likelihood of intersecting fractures. They are mostly adjoining the major faults. There are now around 40 wells drilled in Mauddud including horizontal and multilaterals, most of which became non-producers due to above reasons. A study has been carried out to evaluate opportunities to revive these wells through available and new technologies in the industry. A detailed geological study incorporating all the available data was carried out initially. Wells were screened for stimulation by using various proven new technologies. Acid Frac, Stage Frac, near well bore SurgiFrac and Matrix Acid techniques have been applied with varying results. Advanced placement technique like distributed temperature profiling was used in some of the jobs. This paper presents the details of the application of the above mentioned technologies, to the candidate wells and discusses the results. The success of some of these technologies opened up new opportunities for a new beginning to revive the closed wells completed in Mauddud Formation.

Acid systems are widely recognized by the oil and gas industry as an attractive class of fluids for the efficient stimulation of carbonate reservoirs. One of the major challenges in carbonate acidizing treatments is adjusting the convective transport of acid deep into the reservoir while achieving a minimum rock face dissolution. Conventional emulsified acids are hindered by several limitations; low stability at high temperatures, a high viscosity that limits pumping rate due to frictional losses, the potential of formation damage, and the difficulty to achieve homogenous field-scale mixing. This paper highlights the successful application of an engineered low-viscosity retarded acid system without the need for gelation by a polymer or surfactant or emulsification by diesel. An acid stimulation job using a new innovative retarded acid system has been performed in a West Kuwait field well. The proposed acid system combines the use of a strong mineral acid (i.e. hydrochloric acid "HCl") with a non-damaging retarding agent that allows deeper penetration of the live HCl acid into the formation, resulting in a more effective stimulation treatment. The retardation behavior testing includes dissolution experiments, compatibility testing, coreflood study, and corrosion rate testing (conducted at 200°F). The on-job implementation included the use of a packer to pinpoint fluid pumping (pre-flush) at the point of interest, followed by the customized novel retarded acid system for improving conductivity at perforations and effective reservoir stimulation. This acid system is characterized by having a low-viscosity and high thermal stability system that can be mixed on the fly. This approach addresses the main challenges of emulsified acid systems and offers a cost-effective solution to cover a wide range of applications in matrix acid stimulation and high-temperature conditions that require a chemically retarded acid system. The application of this novel acid retarded system is a fit-for-purpose solution to optimize the return on investment by maximizing the well production and extending the lifetime of the treatment effect. This new system also offers excellent scale inhibition and iron control properties which eliminates the need for any acid remedial work, making it an economical approach over other conventional acid systems. The paper presents results obtained after stimulating the carbonate reservoir and describes the lessons learned from the job planning and execution phases, which can be considered as a best practice for application in similar challenges in other fields. Proper candidate selection, best available placement technique, and lab-tested formulation of novel retarded acid system resulted in achieving 1700 BOPD of oil production (27% higher than expected).