A polycrystalline diamond compact (PDC) bit was used to drill a northern Kuwait well. The typical casing design for this field calls for the 16-in. section to be the longest section in the well, which extended from 1,230 ft to 6,000 ft for a total of 4,770 ft in this particular well. The formations drilled in this section were mainly comprised of carbonates interbedded with shale. The first 2,000 ft of the section was highly interbedded with hard and soft layers of carbonates with the unconfined compressive strength ranging from 6,000 psi to 30,000 psi. Additionally, the remainder of the section had hard stringers with unconfined compressive strength up to 30,000 psi. Such highly varying and highly interbedded formations tend to damage the PDC cutters because they are more susceptible to impact damage. For this reason, roller cone bits with tungsten carbide inserts (TCI) are preferred and are typically run in this section. However, the rate of penetration (ROP) significantly decreases when the TCI bits drill through the hard formations. For this reason, the operator and service provider established an objective to design a PDC cutting structure that would efficiently drill through the hard interbedded formations and complete the section in one run, achieving higher ROP than was achieved with the TCI bits in the offset wells. Based on the formation strength information available, the decision was made to initially use a 6-bladed 16-mm cutter. The service provider then recommended using conical diamond elements (CDEs) and placing them behind the primary PDC cutting structure. The conical shape of the CDEs penetrate the high-compressive-strength rock, effectively weakening the formation with a plowing mechanism. Furthermore, the CDEs also protect the PDC cutting element from impact damage. A high-performance motor was also recommended to reduce stick-slip. A finite element analysis (FEA)-based modeling system was used to comprehend the dynamic behavior of the bit and bottomhole assembly (BHA) design. The most efficient bit design was selected, and changes in the BHA were recommended to deliver the most stable and optimized drilling system. A detailed drilling parameters sensitivity analysis was performed, and a driller's parameter plan was prepared to provide enhanced drilling parameters for mitigating downhole vibrations. As a result, the CDE bit drilled the entire section, achieving an increase in on-bottom ROP by 24%. In the hard formation—where the ROP of TCI bits would typically decrease—the CDE bit drilled at twice the normal ROP. The CDE bit technology proved to be efficient in what was previously thought to be a roller cone application. By reducing the drilling hours needed to complete the entire 16-in. section, the CDE bit saved the operator 3.5 days of equivalent drilling time.

An operators renewed focus on horizontal well drilling and open hole completions, using Inflow Control Device (ICD) screens, necessitated the use of oil-based drill-in fluids (DIF) to drill and complete their reservoir. The challenges were increased by low reservoir pressure conditions, increasing the risk of drilling fluid invasion and possible reservoir damage. Comprehensive laboratory studies were carried out to evaluate DIF performance and ensure understanding of the possible damage mechanisms produced while drilling, considering the reservoir characteristics and drilling conditions.The customized near-wellbore damage remediation system, with a delay-reaction, was designed based on Mesophase technology. This paper discusses detailed laboratory analysis for the clean-up system and its field applications in Kuwait horizontal wells. The applications included drilling carbonate and sandstone reservoirs, open hole ICD completion, and performing effective cleanup required for maximum production.The effectiveness of the Mesophase clean-up system to remediate reservoir damage and improve producibility was evaluated immediately after well kick off and again after steady production levels were reached. This paper shows the results obtained after the application of the near-wellbore remediation technology.The lessons learnt during the Mesophase application were incorporated on upcoming wells to standardize the operating procedures and improve field performance.

Promotion of horizontal well drilling started with inflow control device (ICD) completion to boost the hydrocarbon production as per the KOC 2030 strategy. Drilling these wells revealed many technical issues leading to stuck pipe due to improper hole cleaning. The rate of penetration (ROP) in the buildup and lateral sections was erratic. Drilling a pilot hole and performing pipe-conveyed logging runs were the main factors contributing to excess rig time. It was observed that drain hole cleaning methods and drilling time optimization needed to be improved. These factors increased rig time by about 40 while drilling many horizontal wells in the North Kuwait (NK) horizontal operation, adding significant costs to the well budget. While drilling these horizontal wells, well design was optimized and the drilling team applied the optimized design that increased hole-cleaning effectively, improved ROP and reduced the logging time. The 6⅛-in. and 8½-in. motorized rotary steer-able systems (RSS) and bottomhole assembly (BHA) systems ran for the first time in Kuwait, drilling 8½-in. build section from Mutriba to the Upper Burgan top formation and 6⅛-in. section in Mauddud carbonates has dynamically avoided down-hole tool failures, doubled the average ROP, and reduced non-productive time (NPT). The pilot hole section was designed and drilled in two phases. In the first section a gamma ray tool identified the formation tops. The second section (zone of formation interest) was then drilled using an 8½-in. tool with a triple-combo RSS BHA. This approach reduced the extensive wireline or tough logging condition (TLC) runs and increased ROP by slimming down the borehole size. The hole-cleaning method was modified by combining pumpout techniques with heavy-weighted pills (MW+2 ppg). This technique was used in horizontal wells, resulting in reduced drilling time and well cost.

In close collaboration with the operator, third party suppliers and the integrated drilling service contractor the first Integrated Drilling Project in Kuwait started in March 2016. The project is being treated as a pilot to assess the value integration can bring to the operator by providing the expertise, new technology and processes for managing drilling risks and improving performance. The project scope includes the provision of all services, engineering and supervision for the well construction process under a lump sum model. The project had an original target start date of June 2016, a year after the contract award. However, in the current challenging oil and gas industry environment, coupled with the operator's ambitious plans to increase oil production, the requirement for drilling more wells to provide the necessary increase in oil output meant that an early start would help in accelerating oil production from the Sabriyah and Raudhatain fields. From the onset, the target was set for exceeding client expectations. It required a very detailed planning approach to avoid potential short-sighted risks that could lead to costly delays. This paper describes the success case of advanced planning of a fully integrated approach. Three primary challenges were identified for the early startup, i.e. drilling rigs readiness, personnel and processes. For the drilling rigs readiness, the main issue was the utilisation of an interim rig requiring major equipment overhaul, including engines, top drive, mud pumps and drawwork, followed by an audit and certification. A specialised and dedicated team was mobilized to manage this operation successfully, and better support the rig contractor, including a rig contractor manager, rig managers, electricians and mechanics. Key project team members were brought in ahead of time, through careful selection to ensure the right competencies, according to the technical complexities and contract requirements. The team in place focused on implementing processes to accommodate operational and engineering optimizations as well as new technologies which could be applied from the first well, in order to improve well contruction cycle and deliver more wells in shorter time to the operator. This required collaboration from both teams including the integrated drilling service contractor and the operator. For ensuring the project readiness, a thorough process assessment was followed for each of the established milestones in the schedule. These assessments covered different functional areas including HSE, engineering, drilling services, third party providers, resources allocation and technology review including cost versus benefit analysis. In result, close collaboration and hard work of integrated team including operator, third party suppliers and integrated drilling service contractor, enabled successful project start-up. The drilling operations commenced three months ahead of plan, exceeding expectations of all project stakeholders.

Sidetracking a preexisting drilled and cased wellbore poses numerous challenges. When sidetracking in an openhole environment, additional verifications of hole conditions are needed, which contribute additional unique challenges. In this type of wellbore, the operators must plan by selecting the sidetracking depth and then ensure that all the objectives are met from a well authorization for expenditure standpoint and geological target perspective. The quality of the openhole window or rathole is of immense concern to operators because this quality ensures that the bottomhole assemblies (BHAs) will pass through the rathole without difficulty. The openhole gauge must be confirmed because it can pose additional risks that might lead to costly multiple trips into the well to ensure that the rathole is in good condition. This paper presents a unique case study in which the operator, Kuwait Oil Company (KOC), was faced with the possibility of geological losses at the kickoff in the wellbore while attempting to sidetrack an existing wellbore. The operator contacted an oilfield services company and requested a unique technical solution to precisely sidetrack the wellbore in the difficult formation containing fractured dolomites, which are known to cause severe to complete losses. While drilling the 12.25-in. section, the BHA became stuck in the fractured dolomitic limestone formation. In this section, the operator had previously experienced severe to complete losses. Because fishing attempts to free the stuck BHA were not successful, the operator decided to sidetrack the wellbore in the open hole using an openhole whipstock. A casedhole sidetrack option was ruled out because reactive swelling shales with producing sands were located above the sidetrack depth; therefore, combining these zones was not practical because of the low-mud-weight limit required for drilling the fractured dolomite below the target depth. In addition, because only 70 ft of open hole existed between the 13.375-in. casing shoe and the stuck BHA in the hole, sidetracking with a cement plug was nearly impossible. The openhole wellbore was logged with a caliper to confirm the wellbore gauge. Prejob planning consisted of understanding the compressive rock strength from the offset wells to identify the lithological challenges unique to this application. A hazard analysis risk-control method was adopted to identify the risks and apply appropriate mitigation measures. An operating parameters plan was formulated by the engineering team and discussed with the operator and service company personnel and followed throughout the job. The wellbore was successfully sidetracked in the 12.25-in. section in a single run using an openhole whipstock, avoiding the loss zone, and resulting in additional cost savings to the operator. The condition of the sidetracked rathole enabled smooth passage of the directional BHA to meet the directional objectives. Furthermore, the openhole whipstock operation eliminated the need for multiple cement plugs in the sidetrack (in view of severe loss zones below) as well as the time required for drilling with a dedicated motor BHA for openhole sidetracking operation, saving the operator a minimum of 6 days of rig time. This operation was the first successful 12.25-in. openhole sidetrack operation in the Middle East, Asia-Pacific, and sub-Sahara Africa regions. As a result of this successful operation, the operator is proactively recommending the new solution across the entire KOC organization for wells with similar scenarios. By applying this unique and reliable openhole whipstock technical solution, the drilling team was able to deliver a successful well based on the original casing plan without any need for further sidetracks or changes to the wellbore casing design.