Drilling through total loss zones without returns at surface is a common practice for Operating Companies in the Middle East. This is known as the Mud Cap/Blind Drilling technique and it has been used for a long time in the region. The lessons learned throughout these years have produced well established procedures and "rules of thumb" for estimating mud density, volume and pumping schedule of the mud cap for different situations. The application of this Mud Cap/Blind Drilling technique becomes more challenging when drilling through oil reservoirs with a high H2S content and combining zones with pressure regimes significantly different in the same hole section. This situation is often the case for some well designs commonly used to re-enter oil producer wells in Saudi Arabia. Under these circumstances, the main well control strategy is to maintain enough of a mud cap to prevent any migration of the hazardous gases and/or liquid hydrocarbons to the surface. This approach often results in a conservative design of mud cap densities and volumes, which in turn generates huge expenditures in mud material and puts tremendous stress on logistics and transportation. The Pressurized Mud Cap technique offers a safe alternative to Blind Drilling. This technique uses regular Managed Pressure Drilling (MPD) equipment to monitor the behavior of the reservoir at all times, improving the safety of the operation, by having accurate well control and realizing substantial cost savings, by optimizing the usage of drilling fluid materials and other resources associated with the mixing and pumping of the mud cap. This paper describes the successful implementation of this technique for re-entering oil wells in an onshore field in Saudi Arabia. The paper also provides details for the equipment and procedures utilized to maintain a full column of fluid under pressure, by keeping the MPD choke fully closed while drilling without any returns at the surface. The results, when compared with the conventional Mud Cap/Blind Drilling Technique, show significant improvements in safety (well control), cost efficiency and logistics.

Over the last several years Saudi Aramco embarked on a technology driven strategy to maximize well productivity and total oil recovery by converting existing weak horizontal producers or dead vertical wells to MRC (maximum reservoir contact) wells. Another application is drilling new MRC wells from surface, many of which, if required by reservoir management, were installed with downhole smart systems to control flow from each lateral. Most of these wells were drilled with cemented 7" conventional liner or worked over with 5–1/2" expandable liner for zonal isolation as well as conduit for smart completion in the reservoir. This paper will present an alternative to convert existing old wells to smart MRC wells equipped with hydraulically controlled downhole valves and swell packers or feed-through open hole packers as zonal isolation in open hole environment. So far four such wells have been successfully worked over and completed with open hole smart completion. Production data shows that not only these wells have achieved significant production gains, but also confirmed that the downhole isolation packers and flow control valves functioned as planned. This paper will also highlight the cost saving advantage of open hole smart completion as well as operational optimization process that led to successful field implementation. Introduction Over the last several years Saudi Aramco has embarked on a technology driven workover strategy to maximize well productivity and total oil recovery by converting existing weak horizontal producers to MRC (maximum reservoir contact) wells, many of which, if required by reservoir management, were installed with downhole smart systems to control flow from each lateral. This strategy has been also applied to convert dead vertical wells to single horizontal producers or power water injectors. A 5–1/2" cemented expandable liner is one of the key drivers that enables zonal isolation as well as conduit for smart completion in the reservoir if required 1 - 4. In a continued effort to save rig time and reduce well cost, a bold strategy was reviewed to consider a possible deployment of open hole smart completion in MRC wells. The idea was to set isolation packers and downhole hydraulically operated ICVs (interval control valves) in open hole instead of in cased hole. A first trial test to implement open hole smart completion was scheduled to be carried out in one of the workover wells in August 2005. The key technology components to meet this objective consisted of swell packers with feed-through control lines for zonal isolation in open hole, and hydraulically operated ICV. The swell packer was tested in Saudi Aramco R&D lab prior to the field application and was concluded to be suitable for field installation 5. The technical data for the swell packer is listed in Table 1. The key advantages of utilizing swell packers are (a) simple and robust rigging up procedure with almost no extra time required on rig floor when making up with completion tubing and control lines pass-through (Figure 1), and (b) no hydraulic or mechanical packer setting requirement. The first well, which was a converted MRC well, was able to deliver the expected production rate despite of the difficulties in landing the completion string along the planned motherbore. It nevertheless did demonstrate that such workover strategy would enable up to 10 days rig time saving. After the first well test, a review was conducted. The results limited this type of completion only to converted dual-lateral workover wells, newly drilled or sidetracked MRC wells. A better application case was identified. Subsequently another open hole smart completion was successfully implemented without any problem in February 2006 in one of the converted single to dual-lateral workover well.

This paper describes the successful introduction of ultraslim rotary steerable system (US-RSS) drilling in Saudi Arabia. A case study is presented where a 2167 ft power water injector redrill lateral was successfully drilled in the reservoir using an US-RSS on 2 3/8" drillpipe in conjunction with ultraslim logging-while-drilling tools, which were used for concurrent high accuracy geosteering. The existing casing design required that the sidetrack had to exit the liner in the reservoir section, since sidetracking higher up was not an option because of the risk of exposing problematic formations and pressurized zones. A number of challenges had to be overcome, including engineering design for sufficient weight transfer to be able to drill and good bit selection, since it would have been impossible to drill the planned section with a motor or conventional drilling assembly. Each stage of the job was carefully planned in detail and all stakeholders were briefed and contributed to the plan to ensure that all objectives - both drilling and well placement, could be met. The US-RSS was run in hole to drill the lateral, which was drilled with a 3 7/8" bit and concurrently opened up to 4¼". The US-RSS tool performed as planned and produced an overall rate of penetration (ROP) of 28ft per hour in a single run during the geosteering operation. All well objectives were achieved, and the system clearly demonstrated a robust technical solution to the problem. The US-RSS will enable greater reservoir access, especially in the redevelopment drilling application, and when used in conjunction with ultraslim LWD tools, can also be used to place the well in the best position for optimal additional production. Recovery rates from the field are now expected to be enhanced as a result of this technology, and without the need for drilling further new wells. Introduction Today it is well understood that further opportunities exist to enhance the production from existing fields 1 and to access as-yet untapped areas of the reservoir using a variety of redevelopment drilling techniques. Saudi Aramco faced this challenge with a re-entry program to redevelop an average of up to fifty wells annually in some of these fields, in order to recover as much remaining oil in place as possible. Due to the existing casing design and the formation pressure profiles, the only feasible size for the new drain hole is 3 7/8" diameter, if the existing well architecture is to be used for the redrilling program. However, this hole size is known to be problematic from a drilling perspective in terms of pipe buckling, achieving effective weight transfer to the bit, and the physical limitations of the mud motors that are available for this hole size. This is especially the case with regard to directional control, where the length of lateral that can practically be drilled with the motor is limited by the ability to 'slide' to control the trajectory and maximize the reservoir contact. These issues also result in roller cone bits having to be used to drill in this size, resulting in several trips per hole section, and therefore a lot of 'dead time' being required to complete drilling each well. An alternative approach is to use the recently developed US-RSS to complete these redrill laterals in a single run by rotating continuously while steering, thereby reducing the impact of the buckling forces, and by using a PDC bit. In addition, such a solution to the problem would also conceivably allow for longer laterals to be drilled while staying in the desired layer of the reservoir, thereby giving potentially greater access to the remaining oil-in-place. The US-RSS tool was developed for drilling in this range of hole sizes, specifically for this application, and can be used as part of a standard drilling system run on drillpipe. The system can also be used for coiled tubing drilling applications for 'thru-tubing' drilling 2, which has been documented elsewhere.

Smart Maximum Reservoir Contact (MRC) wells have been successfully utilized extensively across Saudi Aramco to increase reservoir contact, well productivity and total oil recovery. This concept has primarily been used in newly drilled wells. It requires larger than conventional hole and casing sizes to achieve the dimensions required for the Intelligent Well System. Converting an existing well to an MRC poses a new challenge. This paper presents a case history of two old existing dead wells in Saudi Aramco that were successfully converted into the first Slim Open Hole MRC Wells in the world. The two wells were originally drilled as vertical producing wells with 7" 23# liner set above the top of the target zone and extending to surface. To access more reserves from the field, the decision was made to sidetrack the wells to a new location and drill an MRC wells to achieve maximum productivity from those wells. The wells were planned to be a three lateral wells with a total of 12,000' of reservoir contact in each well. To maximize the long term productivity of the wells, it was decided to run Intelligent Well Systems that enables remote monitoring and control of each lateral throughout the life of the two wells. The final success of these converted slim open hole smart MRC wells are supported by more than expected production gain. Introduction The industry faces a general challenge in meeting the well production objectives when a producing field is mature. To reduce well cost and maximize oil recovery, sidetrack is obviously effective approach. However the conventional method entails a significant wellbore ID reduction when curve section is isolated with conventional cemented liner. In addition, delivering smooth wellbore for high cost smart completion equipment was also a very pronounced critical concern. To meet these challenges, three current cutting-edge technologies are adopted and put to use.The first is the 5–1/2" x 7" cemented expandable liner for the effective zonal isolation of the curved section before the reservoir target entry. This technology offers a minimum (10%) hole reduction. Saudi Aramco is at the fore front of utilizing this technology and gained significant field experiences and most important of all, demonstrated a great value added for substantial production gain over the last several years of field applications 1 - 2.The second is the modified rotary steerable system that enables directionally drilling smooth 5–1/2" laterals with full LWD capability. The technology has been shown to substantially improve bit performance, in fact setting many world records recently in Saudi Arabia 1.The third is the slim hole smart completion equipment that functions inside 5–1/2" open hole. This includes open hole packers with feed-through control lines and downhole ICV (interval control valve) in addition to downhole permanent pressure & temperature gauges for reservoir monitoring as well as flow control of laterals at surface. The slim open hole packer was previously utilized successfully in a similar well application to pass through 5–1/2" expandable liner (for zonal isolation of the curved section) and set as compartment tool in 5–1/2" open hole in reservoir for passive inflow control 3.

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