Drilling & Completing of the wells faster, safer and at lower costs has always been the primary target for the operating companies worldwide. While it has been achieved by several means through Technology, Innovation, Operational Optimization, Cost Reduction Techniques, Application of Best Practices etc; the operating company still has to deal with multiple contractors, vendors, suppliers and service providers, with each of them having different drivers for success that may or may not align with the primary goal. The concept of Integrated Operations / Services brings in this required polarization of drivers for success to deliver the projects under budgeted AFE & planned times. In one of such Integrated Drilling Operations Campaign, at an Artificial Island located in Offshore United Arab Emirates, with single focal point for various drilling well services, the learning curve of the project has been very steep with numerous optimization measures taken at the early phase of the project under the continuous improvement process to enhance the drilling efficiency in order to speed up the well delivery. The step change achieved in the drilling efficiency for delivering the 16″ section will be detailed in this paper. The same concept has been applied in other sections with similar success. The drilling optimization has never been so thorough and need of the hour with the current prolonged challenging market conditions. This paper revisits the drilling optimization by integrating all the associated well drilling services to improve and pursue higher drilling efficiencies. It details in steps, starting with identifying the opportunities of improvement, how the traditional methods & practices were challenged and the revised practices were adopted in design & operational execution to better the performance and deliver the section faster consistently with every well. The drilling performance of this section after integrated drilling optimization currently holds several records (best footage/day, best footage/24 hours, best onbottom ROP, best average ROP including connections, best connection times, days/1000 ft, faster casing running speeds) in the subject field and also stands out when compared to the other nearby offshore fields in the country. These drilling performance records are combined with good hole quality which have contributed to delivering the fastest 16″ section when one includes casing running and other flat time activities. With the planned changes alongside the detailed engineering planning & constantly monitored execution, the section has been delivered well after well with improved times. Overall, the drilling phase of this section has been delivered 3 days earlier than the offset wells and contributing to potential savings of up to 18 million USD to the project drilling campaign cost.

The paper will present lessons learnt to mitigate the stabilization of the air/gas entering into lubricious biopolymer water-based system which decreased density of mud while drilling. The system selected for its highly lubricious properties and formation damage free properties to accommodate the usage of resistivity equipment provided excellent results in the field. Performance was almost equivalent to non-aqueous drilling fluid. However, the stabilization of gas/air entering the mud was encountered generating drilling troubles and risk of well control problems. An extensive study performed, consisted of assessing interactions between components and containments of the mud system with gas/air, crude-oil and drill solids introduced from the reservoir. The testing involved the adding of air from air-compressor for 60-second while mud sample is sheared at 6000 rpm. The mud weights of samples were measured before addition of air, right after and 60-second after the aeration. The percentage of density drop was calculated. Target value was maximum drop of 5% within 60 second after stopping the addition of air. Several combinations of polymers, lubricants, contaminants and other additives were evaluated. The study demonstrated that the interactions between crude-oil, polymers and lubricants can highly stabilize air/gas entrapment in the biopolymer water base mud system. The phenomena led to significant density decrease, drilling troubles, well control and safety issue in the field. They can also increase the viscosity of the biopolymer mud system. However, highly stabilized air/gas entrapment can be removed by the addition of emulsion breaker at concentration less than 1.5%vol of mud. In addition, the type and nature of the lubricant plays a major role in the stabilization of air/gas entrapment. The selection of the polymers should be combined with the choice of lubricant during the design phase to minimize the gas entrapment. Knowledge gained from the study establish a new testing protocol to assess in the laboratory the air/gas entrapment close to field shear conditions. The testing protocol showed good correlation with the field. The testing protocol can be used during the design phase or for investigations. It will improve the overall design of mud system where highly lubricious fluid is needed. Combination of polymers and lubricants did also provide low air/gas entrapment tendency.

Because environmental regulations are rapidly evolving towards stringent requirements, oil and gasoperators are confronted with a great challenge of disposing drilling waste, especially when operating on an artificial island located 120-km offshore and under a Zero Discharge Policy. The paper describes an innovative engineering solution that significantly reduces the time, cost and the associated safety hazards with disposing of the cement waste generated from primary cementing operations and drilled cement cuttings. The earlier disposal process implemented on the island included collecting, storing, and shipping the cement waste to an onshore treatment facility. This process was proven to be cumbersome, time-consuming and extremely expensive. Additionally, external factors such as logistics constraints, weatherconditions, and storage skips availability had a direct negative impact on the process, resulting in a massive accumulation of waste on the island. On the other hand, the newly developed disposal process utilizes existing resources, with minor modification, within the artificial island. A step-by-step procedure was developed to dispose all excess cement and drilled cement cuttings generated without any negative HSE impact. A pilot trial was performed successfully by injecting the cement waste into the shallow loss zone through the annulus, and therefore, the process was generalized to both island and found to be safe and efficient operationally and economically. The new innovative method simplifies the disposal process to a one-stage operation that is performed along with the primary cementing operation. By implementing the process, no cement handling on surface is needed, resulting in a 90-percent drop in the cost.. The number of people involved is reduced as well. Consequently, a reduction in the hazard exposure and the potential lost time incident (LTI) is achieved.

Abu Dhabi National Oil Company (ADNOC) offshore and Schlumberger jointly initiated a project to drill the longest 12¼-in section ever drilled in United Arabs Emirates (UAE) as part of the integrated drilling service for an extended-reach project. The plan involved drilling 14,400 ft in an extended-reach drilling (ERD) well in the field. The objective was to reach section TD in one run, drilling from 5,194-ft MD and reaching TD at 19,494 ft MD. In the well in study, Well 29, the trajectory crossed different formations—including limestones, shales, and dolomites—and built inclination from 30° to 78° to achieve an optimal step-out for the following sections to reach the boundaries of the reservoir at 27,000 ft. Different formation challenges throughout the section required a step change in engineering to complete the objective successfully. ADNOC needed a robust steerable system selection with metal-to-metal sealing that would be exposed to severe downhole conditions, a new bit technology design, anti-collision analysis to help reduce additional gyroscopic operations, and optimized drilling parameters with an enhanced drillstring design. The section was planned to drill in 17.7 days. The total section was finished 10 days ahead of planned AFE, setting the record for the longest 12¼-in section ever drilled in ADNOC and UAE of 14,400 ft, which was 58% longer lateral than field average. Through increased cutting efficiency and superior impact resistance, the new bit design with ridged diamond elements drilled the fastest 12¼-in section on the field in 0.91 d/1,000 ft. Good hole conditions facilitated successfully running and cementing the longest 9⅝-in casing, meeting ADNOC well integrity barrier requirements. The 12¼-in section had the fastest IADC-recorded ROP in the field, with an on-bottom ROP of 105 ft/h, which was 110% faster than the field average. The Geomagnetic Reference Service correction was implemented for the first time and was allowed to drill in proximity with a high anti-collision risk well, eliminating a gyro trip in the middle of the run. Downhole drilling parameters analysis from the drilling mechanics module was crucial for understanding downhole energy transmission and implementation of efficient drilling strategy and reducing shocks and vibrations. The drillstring was redesigned, replacing the traditional 5-in × 5⅞-in drillpipe and enabling a stiffer BHA, which helped maximize the bit performance.

This paper seeks to demonstrate how the use of real-time downhole drilling data can help facilitate the timely, well-informed decision to pull out of hole (POOH) if the rate of penetration (ROP) reduces beyond expectation. The traditional decision process starts with offset ROP comparison. If the ROP is lower than expected, then typically there are two scenarios: either the drill bit has become dull or the formation is harder to drill than expected. If the first scenario is suspected then a cost-benefit analysis is performed whereby the remaining footage is assessed and the time to drill to section TD with the current ROP is calculated and compared to the cost of a new drill bit, rig time and the cost of round tripping to change the bit. However, when the bit is on surface and seen to still have good cutting structure then the round trip has been a waste of time and money and more patience should have been exercised in keeping the drill bit on bottom. With real-time, downhole drilling data it is possible to assess the drillability of the formation and estimate the dull condition of the bit. Primary parameters that are used for this assessment are downhole weight on bit and downhole torque, and their relationship to one another. In addition, the trend of the downhole mechanical specific energy is evaluated. The first case study under discussion was drilled in 12¼-in. section, offshore UAE field. For the initial 4,500ft the average ROP was 80ft/hr, at which point a dramatic decrease in ROP was observed. A reduction in ROP was expected at this point because of formation change, but the magnitude of the reduction was much greater. Because the ROP was expected to reduce, the drilling continued with some short-lived increases in ROP. After a sustained time period of low ROP the decision to POOH was made, when the drill bit was on surface the dull grade was 1-6-HC-S-X-I-RO-PR. Upon evaluation of downhole drilling data with the aid of hindsight regarding eventual dull grade it was seen that there were clear indications that the bit was no longer effective and the decision to POOH should have been made. The time period that elapsed between the drill bit becoming damaged and POOH was 30 hours. This base case lesson learned was utilized on a subsequent well in the drilling campaign on an analogous application. By using this downhole signature a quicker, more effective POOH decision was made. The POOH decision in this case was made after just 2.5 hours compared to the 30 hours on the previous well. Once on surface, the dull grade of the bit was 2-7-WT-S-X-I-RO-PR.