This paper explains the successful execution of Expandable Liner Hanger and primary cementing job for ERD wells in Rajasthan block of North-West India. One of these wells has the longest horizontal 6in. hole section in the Indian Subcontinent. Zonal isolation is especially critical, as these wells are all candidates for multistage fracturing operations in the completion phase. The successful liner job in these wells face several challenges: placement of 4½ inch liner in 6 inch hole, hole conditioning, cement placement and ECD challenges due to low fracture gradient limit. An integrated Basis of Design was developed to mitigate the challenges. This includes The placement of liners with computer aided torque & drag analysis,Rotation of liner during hole conditioning & cementing at highest possible rpm within acceptable torque limits,Fine tune fluid properties with computer aided simulator to achieve sufficient cement coverage around the liner (displacement efficiency). The liner hanger system in this case study has an advanced running tool to facilitate the required rotating capability. The liner hanger also incorporates a contingency tertiary setting mechanism for liner expansion due to the challenging down hole condition. The expandable liner hanger is an integrated hanger packer system. Elastomeric elements are bonded on to the hanger body itself. As the hanger body is expanded, the elastomeric elements are compressed in the annular space, which provides primary annular isolation at liner top. This case study also examined the impact of liner rotation on displacement efficiency of the cement slurry with computer aided Finite Element Analysis. The results give engineers a better understanding of the relationship between rpm and displacement efficiency of the cement slurry. The technology and the practices established from this case study have become the standard operating procedures for liner cementing jobs in subsequent ERD wells.

The development drilling campaign for the Ujung Pangkah field in offshore East Java, Indonesia, began in the first quarter of 2007. To prepare for circulation losses, the field operator tendered for managed pressure drilling (MPD) services as a contingency. The first gas well was successfully drilled by relying on conventional lost circulation material (LCM) to minimize the losses encountered. However, after drilling a pilot hole, plugging back and sidetracking the second gas well, total losses were encountered, followed by the persistent migration of gas up the annulus despite seawater bullheading. After stabilizing the well, MPD equipment and personnel were then mobilized and the system was rigged up to allow for clean-out and completion operations. Total losses were again experienced, but MPD made washing and reaming down to the previous depth possible. MPD techniques also kept gas migration in check, allowing for safer tripping operations in and out of the hole. An additional 55 ft of new formation was drilled and completion was run using MPD methods. This gas well has proved to be the most productive well drilled in the field to date. In subsequent wells, MPD equipment was rigged up before drilling the hole sections where severe circulation losses are anticipated. This practice paid dividends when severe losses were again experienced while drilling the first oil well. With the MPD system already installed, drilling was able to resume immediately in MPD mode up to the target depth for the section, despite total losses. Liner running and cementing was then successfully done in MPD mode, allowing for the successful isolation of the zone where the losses were and for drilling operations for the next hole section to proceed immediately. The MPD system in the Ujung Pangkah field has proven its value as a contingency measure by allowing drilling operations to continue despite total loss of circulation and by minimizing the non-performance time involved when the eventuality occurs. Ujung Pangkah Field Development The Ujung Pangkah Field is located in shallow water off the northeastern coast of Java, Indonesia, immediately to the west of the island of Madura (see Figure 1 for the location of the field). The production sharing contract for the Pangkah block, where the field is located, was signed on May 1996. Ujung Pangkah-1, the first exploration well drilled in the area, flowed at rates of 20 mmscf/d and 987 bopd through a restricted choke. The discovery was announced in November 1998. The Ujung Pangkah appraisal program, which was completed in 2004, confirmed reserves for the field in excess of 450 bcf of rich gas with the possibility of developing additional oil from the structure. The Ujung Pangkah oil rim underlying the gas accumulation has approximately 450 million barrels mapped in place. In December 2004, it was announced that an agreement was finalized for the sale of gas from the Ujung Pangkah Field. The agreement provides for the supply of 440 billion cubic feet of natural gas from the field over a 20 year period at an expected plateau rate of 100 million cubic feet per day (gross). The gas will be delivered from the field to the Indonesian State Electricity Company's (PLN) 2,200 MW gas-fired power station, at Gresik near Surabaya, East Java.

Managed Pressure Drilling technology was deployed to drill Cairn India's first HTHP offshore well in Ravva offshore field of India. MPD feasibility study was carried out initially and this well proved as a candidate well for MPD in hole sections where narrow margin between pore pressure and fracture pressure exists. The use of MPD was further substantiated to mitigate non-productive time associated with wellbore problems like wellbore ballooning, kicks, loss circulation and stuck pipe which were encountered in offset wells. Therefore, a constant bottom hole pressure technique was chosen with mud weight closer to pore pressure & ECD profile being kept according to selected anchor point for each hole section. The fully automated MPD set-up comprising of a rotating head (with dual sealing function), MPD choke manifold and Coriolis flow meter (6” & 4”) guided by real time hydraulic modelling was used in the well. The mud program was designed close to pore pressure in conjunction with MPD, reduce ECD while drilling and maintaining rheology at high temperature. The deployment of MPD enabled to increase the section length of the 12.1/4” hole section (769 m), which proved to be a key step in in order to accomplish the well objectives in deeper sections. This paper by medium of actual case study talks about use of MPD technology, operational/ equipment problems faced and lessons learnt. This paper also highlights recommendations for use of MPD technology for similar wells.

Cairn India is an operator carrying out development and exploration drilling in the RJ-ON-90/1 area on land in Rajasthan, India. The block is approximately 3000 sq. km and there have been over 400 development wells and 52 exploration wells drilled since 2009. CIL as an organization decided to adopt best practices in all aspects of its operations including environmental management. This paper addresses how the use and optimization of cuttings dryer technologies has led to improved efficiencies in waste management while maintaining environmental targets without increase in costs. The optimization process also has a positive impact on waste management HSE aspects by reducing the number of units being used and improving process control. A ramp up in drilling activity between 2013 and 2015 resulted in significant quantities of drilling waste (hazardous cuttings waste generated from drilling with Synthetic Based Mud) that threatened the overflow of the CIL hazardous landfill site located at the Mangala Processing Terminal. With environmental regulations becoming more stringent and land costs increasing steadily, the Company had to re-think its approach towards waste management. The presence of hazardous drilling waste is not only an environmental concern but an operational challenge for the Company. During the rainy season, the rainwater turns the hazardous solid waste into slurry thereby resulting in hazardous liquid waste. This liquid is extremely difficult to treat and nearly impossible to reduce by evaporation. With rainwater filling the waste pits at the rig site, this hazardous liquid waste may flow into the adjacent lands destroying crops and imposing a threat to cattle that may drink the water. The key was to treat hazardous solid waste as soon as possible and dispose of the residue into the landfill. A primary target for improvement in effective management of hazardous drilling waste solids is to process all the generated hazardous waste in order to reduce oil-on-cuttings (OOC)% to an acceptable level prior to disposal, and if possible recycle as much recovered fluid (base oil/emulsion) as possible. The maximum OOC as per the Central Pollution Control Board, India is 10gm/kg for the cuttings to be safely disposed of in lined pits. Centrifugal / Vertical Cuttings Dryer units are often used as a part of waste management strategies on both onshore and offshore rigs. VCD manufacturers build units which to date have primarily been installed at the rig sites, and are plumbed directly into the shakers by means of screw conveyors that transfer the cuttings from the shakers directly to the VCD unit. This paper illustrates that in cases where multiple VCDs are required, the number of units may be optimized with minimal loss in base oil recovery and such optimization may also deliver cost benefits dependent upon drilling activity levels. Additionally, reduction of waste pit requirements has the potential to reduce environmental footprint along with increased cost savings. Using SBM with reduced environmental impact may potentially increase the usage of SBM allowing for greater technical choices during well bore construction.

In a technically challenging & high cost environment such as HTHP wells, careful selection and adoption of advanced technologies for the successful completion of the well is paramount. As per the original well design of the subject well, it was planned to drill with a bit & under reamer which was actuated by a ball drop mechanism. This led to the restriction of placing the under reamer close to the bit as MWD/LWD had limited pass through & hence the under reamer had to be run above the tools leaving approximately 25-30 m of rat hole un-opened along with inability to retrieve radioactive source in an event the BHA was lost in hole. This required two separate BHA runs to open the rat hole in order to place the casing shoe as deep as possible. The additional hole opening trip would have resulted in extra time and hence additional cost, moreover it was prudent in HTHP well to place the casing shoe exactly at right depth to achieve well objectives. Hence, use of Bi-center bit to simultaneously drill & under ream without any pass through restriction was evaluated. Several critical issues, related to application and BHA design, were faced by the Well Engineering team. Reaming while Drilling (RWD) with bi-center bits has always been challenging in terms of vibration-related inefficiencies. Due to the asymmetrical geometry of the bit, imbalances in force and mass have been responsible for the vibration related problems. Secondly, due to the minimum pass through requirements, these assemblies are virtually always run with under-gauged stabilizers as it allows a certain degree of lateral movement within the constraints of the enlarged hole. All of these issues could have caused the pilot-bit drilling an over-gauged hole along its axis which results in the bit drilling off center giving an overall under-gauged hole as the pilot of the bit is not centralizing the reamer. A unique eccentric vibration dampening tool (ideally located in the string) was used to mitigate the drillstring vibration & bit whirl. This paper describes the well specific BHA design & placement of the vibration dampening tool used to improve hole opening performance. A total of 4 bi-center bit runs over three hole sections & different sizes i.e.12.¼″× 14.¾″, 10.3/8″ × 12.¼″ & 5.7/8″ × 6.¾″ are also discussed in the paper. Unusual problems were encountered while drilling shoe track & landing collar for liners in 10.3/8″ × 12.¼″ and 5.7/8″ × 6.¾″ hole section. Lessons learnt, recommendations & contingencies to be planned for successful application of bi-center bit are discussed.