Globally, many thousands of potentially productive oil and gas wells suffer internal corrosion due to H2S, CO2, and other produced gases and liquids. This limits their capability to provide a packer sealing area suitable for traditional mechanical production packers. Total E&P Qatar planned a recompletion using intelligent well technology in a well in which they expected to find some corrosion. Before initiating the recompletion, they investigated the use of alternative packer technology. Swelling elastomer packers have been used worldwide in many applications, but verification was required in this case to assess whether such packers would hold pressure in a corroded section of casing. In addition, testing was also was needed to assess whether the completion could be pulled in the event that it became necessary to retrieve the components from the well. A swellable packer with multiple cable feed-through was designed and manufactured to approximately two-thirds size of the originally specified packer. A sample of corroded casing, supplied by Total E&P Qatar, was used to build a test jig. The jig was equipped to simulate and record pressure, temperature, and other downhole conditions. Theoretical simulations were performed to assess the force required to overcome the anchoring forces applied by the swelled elastomer and were verified by a pull test. It is expected that with a reliable sealing mechanism for these older wells, technically and financially viable workovers and re-completions can be performed, thereby extending field life and adding to recoverable reserves. This paper describes the application and test procedures along with the verification and results of the testing performed. Introduction The Al Khalij field lays 100km offshore Qatar in 60m water depth. The first discovery dates back to 1991, when the Mishrif reservoir was confirmed as oil bearing. The field was developed in a phased manner to reduce developmental risks and to optimize development cost. First production from the field was delivered in 1997. At the end of 2005, three phases of development of the field had been completed, and currently, an infill drilling program is in progress. Presently, this vast field is produced through seven unmanned wellhead platforms and one water-separation platform. A total of 37 oil producers, six water injectors, and four water producers have been drilled and completed to date. Due to the proximity of the aquifer, significant amounts of water are produced. Owing to the sub hydrostatic reservoir pressure, producer wells are equipped with Electrical Submersible Pumps (ESPs). The electrical generation necessary to power the ESPs is located on Halul Island, located 45 km away from the field as shown in Fig. 1. Most of the water produced is separated offshore on a process platform and is re-injected into the field with the water injector wells aiming at sustaining reservoir pressure. Additional water is produced from the Umm Er Radhuma shallow aquifer and re-injected into the Mishrif reservoir in order to achieve a full voidage replacement and further sustain reservoir pressure.1,2 The Mishrif carbonate reservoir is comprised of several thin stacked layers (three to five meters thick) with a wide range of permeabilities (five to 300mD). In order to increase the Productivity Index and the drainage area of the oil producer wells, they usually feature long to very long cased horizontal drains, which are among the most ambitious ones in the industry. Nearly all wells drilled after year 2000 feature drain lengths in excess of 2000m (see Fig. 2).

The thin and laterally extensive Al Shaheen reservoirs are developed with extended reach horizontal wells and large-scale water injection, which over the last decade has proved to be a proficient and environmentally favorable recovery scheme. This paper describes how injection water short circuiting between two horizontal wells in excess of 20,000 ft was eliminated with a conformance treatment without the necessity of a costly and operationally risky well intervention. Traditionally, reservoir management in terms of injection or production profile modification has been achieved with rig-based work-over operations applying mechanical solutions such as cement or isolation straddles. Work-over operations utilizing drilling rigs are, however, expensive, pose inherent operational risks and delay the implementation of the ongoing development plans. When water injection was recently commenced in a well taking part of an existing line drive pattern, an immediate pressure and watercut response was observed in the adjacent producer. Attempts were made to mitigate the effect of the communication, but water injection eventually had to be ceased to allow sustainable flow from the production well. The very pronounced response in the producer suggested that short circuiting was occurring through a fracture providing conductivity several orders of magnitude higher than the prevailing matrix conductivity. A comprehensive multi-disciplinary review of static and dynamic data lead to the assessment that the fracture communication could be eliminated utilizing a conformance treatment and following laboratory testing and design, a crystalline superabsorbent copolymer was pumped from a stimulation vessel as part of an intervention- and rig-less operation. After the conformance treatment, injection was resumed with no adverse effects on the performance of the adjacent producer. The treatment is estimated to have recovered lost oil reserves of some 3 MMstb and to have reduced cost with more than USD 8 million compared to a conventional rig-based work-over operation. Introduction Maersk Oil Qatar is the operator of the Al Shaheen Field located on the central axis of the Qatar Arch some 70 kilometers north-east of the Qatar peninsula (Figure 1). The main reservoir targets include the Lower Cretaceous Kharaib B and Shuaiba carbonate formations and the Nahr Umr sandstone (Figure 2). The Kharaib reservoir is a laterally uniform carbonate platform with a full thickness of 80 ft and a reservoir target of some 10 ft. The reservoir comprises tight carbonates with inter and intra granular porosity and local natural fracture networks. The Shuaiba reservoir is a transitional marginal carbonate platform with a full thickness of approximately 200 ft thick and a reservoir target of some 20 ft. The reservoir comprises tight carbonates with inter and intra granular porosity and local natural fracture networks. The Nahr Umr reservoir comprises laterally extensive marginal marine sands with a target thickness of some 5 to 10 ft of unconsolidated, high permeable sand.

Although drilling technology is now able to deliver ultra long horizontal wells (LHWs), completion technology has been slower to evolve. Running long liners, effective stimulation, and completions are some of the areas that require more attention. This paper discusses some of the challenges in the development of the Al Shaheen reservoirs offshore Qatar and how they were overcome. Some of these wells have a stepout in excess of 30,000 ft with a total vertical depth of 3,100 to 3,500 ft, and thus, they offer some unique challenges. Running and cementing liners to these depths is difficult, and some of the methods to achieve this effectively are discussed. Perforating guidelines are presented that allow sand control without having to resort to conventional sand-control practices. Stimulation of such long reservoir sections is a particular challenge, and a fine balance must be struck between acid coverage and cost, both for barefoot and perforated intervals. The so-called Q-CAJ technique of acid distribution, which has allowed acceptable stimulation despite these conditions, is presented. The technique also offers opportunities to stimulate long horizontal boreholes more effectively and at lower cost. Some of the wells are completed with multizone selective completions, which push the design limit of equipment. A number of such intelligent wells have been completed successfully, and more aggressive wells are planned. To optimize the development cost, dual-lateral wells have also been drilled with complete control over each lateral. Discussed are some of the underlying completion techniques such as running completion in stages, use of mechanical latches, hydraulic-control-line wet connects, interval control valves, and limitations imposed by control lines. The paper concludes with some of the challenges that have yet to be overcome.

This paper describes a case study of planning, drilling, completing and production of an extended reach horizontal infill well in the giant Al Shaheen oil field, offshore Qatar. The completion has been designed with three surface controlled zones. The completion is supplemented by a straddle on mechanical open hole packers to isolate a section which has higher risk of pre-mature water breakthrough. This completion provides flexibility for selective production, production testing and performance monitoring. Seven infill wells were planned in the Shuaiba formation for optimization of oil recovery. The first wells were brought online with higher than expected water cuts. A completion was designed for the fourth well in the area to improve reservoir management and liquid handling. The well was successfully drilled with a long step out in order to avoid installing a cemented liner for well spacing purposes in the inner section. The completion was designed based on the downhole logs and record of mud losses while drilling and was installed to 15,000ft. The completion consists of surface controlled sliding sleeves and a ball valve complemented by a pressure gauge and chemical injection. The completion was installed inside a predrilled liner which separated the liner section into zones by timer set mechanical open hole packers. In addition a straddle was installed to isolate a natural fracture zone in the outer part of the well. The completion was run and installed successfully and selective production testing has been conducted. The results show that the three zones have water cuts ranging from 5 to 50%. Selective control of the completion helps to optimise oil production and minimise water production as an integral part of an intelligent field management strategy. Net gain from this completion amounts to some 4,000 stb/day.

TX 75083-3836, U.S.A., fax +1-972-952-9435. AbstractOver the last decade, TOTAL E&P Qatar had taken every opportunity to enhance the performance of Al-Khalij field while mitigating operational associated risks by implementing the new technologies offered by the Oil and Gas industry.The recent technology implemented by TOTAL E&P Qatar, in October 2008, is the DuaLife Pod system. The aim of implementing this technology is to gain the following benefits:• Reduce operational costs by decreasing the number of wells workovers.• Reduce deferred production by having a redundant ESP in case the main ESP fails.• Well-protected ESP, increasing the run life of the well completions.• Prevent further degradation of damaged or corroded production casing. This paper will discuss the processes implemented from conception, design, preparation and procedures for the successful completion of this DuaLife system implemented recently in one of TOTAL E&P Qatar wells. Also the paper will highlight the best practices and lessons learnt from this initial implementation for future implementations.