Drilling to the targeted depth of a well can be a challenge, considering the problems that may arise in the form of wellbore instability, mud losses, and/or differential sticking. The objective was to successfully drill a first-time implementation of an Oil-Based Mud (OBM) system with 60:40 Oil-Water Ratio (OWR). The OBM system was maintained within the specified parameters in terms of mud weight, viscosity, and fluid loss. The addition of primary and secondary emulsifiers in the system enhanced electric stability (ES). Moreover, solid control equipment will be monitored continuously for immediate action if necessary. Contingency plan and a surplus of chemicals will be provided to ensure a smooth drilling and a swift movement of operations. A fluid system was designed after extensive laboratory tests to analyze the optimal approach to drill using the first-time application of 60:40 OWR mud. It reduces the use of Diesel consumption by 26% in total OBM formulation, lowers the percentage of Low Gravity Solids (LGS) compared to the 80:20 OWR mud, and decreases the impact on the environment. Furthermore, the OBM was then reused in consequent wells with the addition of emulsifiers to reduce the cost. This paper presents successful first-time applications of the 60:40 OWR fluid till the targeted lower Burgan formation, interbedded sandstone and shale formation. A complete laboratory analysis comparison between previous wells drilled and the current application indicates no difficulties were faced.

Kuwait Oil Company (KOC) has recently drilled the first multilateral well in a North Kuwait field to improve oil production in productive layers subjected to water coning problems by increasing reservoir exposure using Level 4 multilateral technology. The multilateral well targeted the same sand in different directions with two laterals. Both of the laterals were drilled using rotary steerable drilling systems to reduce drilling time. The drilling process used a full suite of logging while drilling (LWD) tools, including azimuthal deep resistivity technologies, to ensure the well path is precisely geosteered within the reservoir boundaries and density/porosity tools in real-time, combined with specialized modeling software to position the well in the best possible reservoir.Level 4 multilateral technology was selected after performing an extensive geological assessment and studying the challenges of exploiting oil in the target sand reservoir. The 12 1/4-in. main section was cased and cemented with 9 5/8-in. casing to the landing point; the 8 1/2-in. lateral-I was drilled and completed with 5 1/2-in. inflow control devices (ICDs). The sidetrack was performed by cutting a window from a specialized latch coupling in the 9 5/8-in. casing; the 8 1/2-in. section was drilled to the landing point, and the 7-in. liner was run and fully cemented. The 6 1/8-in. lateral-II was drilled and completed with 4 1/2-in. ICDs.The fully cemented and cased junction or bifurcation should help achieve greater well integrity and prevent fluid migration from the adjacent area, while the specialized latch coupling should help ensure easy access to either of the laterals, as required. The ICD technology and swellable packers were selected to delay water breakthrough from an active aquifer.This publication describes the application of multilateral and geosteering technologies, and analyzes the advantages and disadvantages of the first multilateral well drilled in North Kuwait that began with a campaign of higher order (Level 4) multilateral. The well is considered to be a pilot well to identify the feasibility of using multilateral technology as a production model to help enhance oil recovery and reduce drilling costs in the field by replacing the cost of drilling new wells.

Objective/Scope (75) Oilmen have always strived to break technological barriers to reach new heights in searching of Black Gold. In order to create an effort to do so has created world record by drilling the longest Slim Hole Horizontal section in of its deep development well in North Kuwait. The sick well lying dormant was completed as Horizontal Water Injector well through depleted Carbonate zone to augment reservoir pressure and increase oil production in producers. This re-entry well used Ultra Slim drilling technology in order to maximize oil production in the carbonate reservoir. The objective was to support the water injection campaign nearby producer wells in the eastern flank of the field. Limited slim hole logging tool without azimuthal capability and high expectation from client required extra control while drilling with precise geo-steering adjustment. Inability to transmit load during sliding due to sinusoidal buckling in long ultra slim hole, restricts penetration rate and pose challenges to maintain proper wellbore placement. Based on previous experience, we planned to drill this well in multiple runs. Methods, Procedures, Process (75-100) Geo-steering pre well modelling is required to be done prior to job execution. The application engineer also worked based on the offset well drilling data to optimize the bottom hole assembly. There was a concern regarding weight transfer, as Sinusoidal Buckling and the subsequent sliding issues are always difficult for this wellbore size. Ultra Slim Hole tool provides only gamma ray and resistivity logging while drilling tool with the current technology. Log responses incorporated with drilling dynamic and drilling parameters data in real time will be the source and justification for the wellbore placement. Results, Observations, Conclusions (100-200) Slim Hole Motor successfully drilled the long slim lateral section in one run only which otherwise required multiple runs in previous wells drilled by competitors. Despite the challenges, the logging tools allowed proper wellbore placement and wellbore was successfully maintained inside the target porous reservoir. 4.125inch Talon PDC bit endured drilling stresses and OBM helped reduce friction factor and minimize differential sticking while drilling. The well was successfully executed to total depth covered total footage of 4696 feet, making it the longest ultra slim hole horizontal well in the World. The single run job significantly reduced the drilling cost while drilling the Ultra Slim lateral section. The BHA achieved the required sliding capability to steer the well according to geological observations. The sinusoidal buckling concerns were overcome by finding the weak intervals of weight transfer in the BHA and mitigating them with continuously changing the BHA design by reshuffling the drill collars to get the required WOB. Novel/Additive Information (25-75) This will be the world longest Ultra Slim lateral section in single run with no failures.

For the last 20 years, exploration in Kuwait has focused on finding commercial quantities of high quality oil in the deeper high pressure/high temperature (HTHP) Jurassic formations (13,000–17,000 ft), and for gas within the Triassic formations (17,000–21,000 ft). The HPHT conditions, the presence of H2S and CO2, the narrow pore pressure/fracture pressure (PP/FP) window to work with, and the high mud weights (18–20 ppg) required have made deep drilling conditions in Kuwait some of the most challenging in the world. This paper discusses the outstanding drilling performance achieved in drilling Ruadhatain 206 (RA-206) as the fastest deep Jurassic well to date in North Kuwait. New practices were incorporated and several firsts accomplished through optimum utilization of local built-in experience, combined with the latest technology and practices developed by International Operating Companies (IOC's) and service companies. Optimum bit selection resulted in a world record bit run in the 28" section, and record firsts for Kuwait in the 22" and 16" sections. Careful analysis of offset data and in selecting mud weights resulted in improved hole stability with minimum mud losses, and enabled the bottom two hole sections to be commingled. Extensive cement design and optimization resulted in an excellent CBL being achieved in the production casing. The excellent performance achieved in well RA-206, has now opened the possibility of efficiently drilling similar wells in 100 days (technical limit) instead of the 170–200 days normally taken. (Fig-1) The improved drilling practices significantly reduced the drilling time and well costs, and provided a step-change forward in KOC's understanding of drilling limits when applied to deep exploratory/development wells. Background on Kuwait Geology and Jurassic Well History Most Kuwait development and oil production comes from the shallow Cretaceous formations which extend down to 12,000+ ft, and which have normal pore pressures of less than 12 ppg. These formations consist primarily of sequences of sands, limestones and shales. The massive Burgan field of Kuwait is a good example, where multiple stacked oil zones exist in reservoirs ranging from the Wara formation down to the Minagish Oolite. These shallower formations contain a variety of challenging drilling conditions. The near surface formations are prone to loss circulation throughout Kuwait, with the highest severity of losses in the Tertiary Dammam limestones and the Cretaceous Shuaiba formation, both of which contain vuggy fractures. These formations often experience total losses while drilling, and are commonly penetrated using mudcap drilling techniques. Cretaceous shales in the Ahmadi and Ratawi formations are highly reactive, and require inhibitive muds to prevent hydration and hole sloughing. Hole stability is a concern in the Burgan sand/shales and in the depleted Mauddud formation. Hard and very abrasive sands exist in the Zubair formation, and dense carbonates in the Makhul formation result in slow rates of penetration (ROP's) at the bottom of the Cretaceous. Four casing strings are required to safely isolate the Tertiary and Cretaceous sequences prior to entering the overpressured Jurassic sequences below. With the shallower horizons extensively developed in Kuwait, exploration efforts have focused increasingly on drilling into the deeper Jurassic Najmah/Sargelu and Marrat formations. Penetrating into these Jurassic sediments poses significant additional drilling challenges.

In horizontal holes, several factors are affecting formation resistivity. The electromagnetic waves generated from the LWD tools are covering the adjacent beds and the reading can be highly affected. Moreover, when the well trajectory is cutting a bed boundary at a high angle, polarization horns are causing severe noise that masks the true formation resistivity. Recently, several wells in KOC had suffered the above mentioned effects causing great ambiguity in water saturation determination. Moreover, the use of LWD with natural radioactive sources has been always a big concern to KOC. An alternative option to resistivity was proposed to KOC based on using Sigma. The technique incorporates Pulsed Neutron Generators and acts as a multi-purpose measurement (Resistivity / Density / Neutron / Sigma / Spectroscopy). In addition, the technology can be used Sourceless. This technology was used for the first time in Kuwait with great success. The Sigma was used in the water saturation calculations. In addition, a time lapse Sigma was done where a second pass was recorded while pulling out of the hole. A comparison between drilling Sigma and reaming up Sigma was used to indicate any water movement by OBM invasion. Spectroscopy was also used for formation evaluation specially clay content. This is rather useful in complex lithology especially when the Gamma Ray reading is affected by strange mineralogy, thus affecting mobility calculations for accurate ICD design.