Pressurized Mud Cap Drilling (PMCD) and Early Kick Detection (EKD) are two unconventional drilling techniques that have been used widely individually, mostly in relation to closed and pressurizable systems and to Managed Pressure Drilling (MPD) applications. However, both techniques are seldom used together as an integrated setup. This paper describes a synergized PMCD and EKD setup and field deployment that was used to successfully drill a well in offshore Kalimantan, Indonesia that had a high pressure formation below a zone prone to severe circulation losses. The key components in the setup were a rotating control device (RCD) and a Coriolis mass flow meter. Using an RCD, the drilling system was converted from a conventional open-to-the-atmosphere to a closed-loop system that allows more precise diversion and accurate well flow monitoring, when used in conjunction with a Coriolis mass flow meter. Since it is a closed system, the comparison of the flow coming out of the well with the flow pumped into the well will provide advance information regarding any influx or outflux from the system. The system designed also takes into consideration the efficiency in switching between modes, that is, from conventional drilling to PMCD mode or to EKD mode and then, back to conventional mode. Possible improvements to the system and equipment are also discussed in the paper, as well as how the current system was utilized to successfully drill a well that previously involved multiple sidetracks when attempting to drill conventionally to target depth.

The development of the Kanowit Field in offshore Sarawak, Malaysia requires the drilling of two subsea development wells using a semi-sub rig. Previous experience identified the need for solids-free drilling fluid to ensure maximum reservoir productivity and so that the quality of the produced gas is within required specifications. High reservoir pressure requires the use of high-density solids-free drilling fluids, but associated costs and the high probability of losing large volumes to the fractured carbonate reservoir made this option unsuitable. A more cost-effective option was to use a less-dense solids-free drilling fluid and utilize managed pressure drilling (MPD) to be able to compensate for the difference in density with backpressure. MPD mitigated the loss circulation risk by controlling the level of overbalance to the minimum and MPD early kick and loss detection capabilities, used in conjunction with a statically underbalanced drilling fluid, also allowed for the collection of actual geopressure environment data that aided in the decision making process. Both wells were completed and tested with a maximum potential flow rate that exceeded the technical potential in initial projections. The successful deployment of MPD with solids-free drilling fluids proves its technical and economic feasibility in carrying out subsea development drilling through carbonate reservoirs prone to severe circulation losses.

Managed Pressure Drilling (MPD) has been successfully used by a number of operating companies in both onshore and offshore applications in Asia Pacific. Over 100 wells have now been drilled in the region using MPD techniques. MPD has delivered significant cost savings in almost all of the applications. The high cost of offshore drilling means that offshore MPD deliver significant cost savings when non-productive times associated with fluid losses or well control events are eliminated. MPD has now been successfully used on all the types of offshore rigs from platforms, tender rigs, jack-ups, semi-submersibles as well as drillships. Both subsea and surface stacks on floaters have been used for MPD. Drilling with a so-called "closed wellbore" using MPD equipment for drilling operations has now been proven to be beneficial on all rig types and almost all well types. All drilling, logging and completion installations can be safely executed when using MPD equipment. On most installations, only minor modifications are required to enable a closed wellbore drilling system, which in turn enables More Productive Drilling. This paper describes the experiences with MPD equipment installations on floating rigs and on fixed installations in Asia Pacific and it provides some of the lessons learned when using MPD equipment and technologies. Introduction Since 2005, over 100 wells have been drilled using MPD techniques by a number of operating companies. MPD has delivered direct cost and time savings by eliminating the non-productive time associated with losses and other related well control events. Being able to control wellbore pressures by using a closed wellbore system and introducing the application of some simple techniques has allowed previously "undrillable" wells to be successfully drilled to TD. Operators plan and budget wells for a certain number of days and then find that in the best case some 20% time spent on curing losses and kicks is added to their well times. Yet other operators have encountered losses and well control issues that double or even triple their planned well timings. Exceeding planned well times not only pushes drilling budgets past acceptable limits, but it also has a knock on effect on the rig sequence especially if the rig is shared by other operators in the region. Rigging up MPD equipment has allowed successful drilling of the fractured carbonates on all of the wells where the equipment was rigged up Not all of the wells encountered losses, and on these wells the equipment was rigged up but not used. On the wells that did encounter the loss/kick scenarios, MPD enabled all of these wells to be drilled to TD without significant delays. Reasons for MPD The main application of MPD in Asia Pacific is in the drilling of fractured carbonate formations such as Baturaja and Kujung in Indonesia. Total losses are often experienced when fractures and vugs are encountered, and once fluid hydrostatic is lost, gas in the upper part of the carbonate reservoir migrates rapidly to surface, resulting in a well control situation. Once the losses are cured and the well is brought under control, drilling resumes until the next fracture is encountered. At that point, the entire process of killing the well and curing losses often repeats itself. Curing the losses with LCM, gunk squeezes or cement can be successful, but very often this has detrimental effects on the productivity of the reservoir. Using underbalanced drilling (UBD) techniques is not suitable as delivery from a fractured carbonate reservoir can be large and handling large volumes of hydrocarbons on an offshore rig whilst drilling adds to operational complications. Furthermore, crew size and equipment spread for an offshore UBD operation becomes a further limiting factor in the application of UBD offshore. The ability to drill these wells using MPD techniques has been proven to be highly successful.

Studies have revealed that gas kicks unintentionally entrained in oil or synthetic based mud in deepwater drilling operations at water depths greater than 3000 ft are unlikely to break out of solution until they are above the subsea BOPs. The rig diverter is conventionally used to vent riser gas with minimal control and with considerable risk and environmental impact through the uncontrolled discharge of drilling fluids. Riser gas handling (RGH) systems currently being offered provide a reactive solution to the problem by supplying a riser joint equipped with additional components for this specific purpose. This joint is normally composed of a retrofitted annular BOP and a flow spool with hoses that is installed on top of the rig marine riser. An alternative and proactive approach to riser gas handling, which we prefer to call riser gas risk mitigation, is proposed by utilizing managed pressure drilling (MPD) equipment. MPD involves the use of a rotating control device (RCD) to create a closed and pressurizable drilling system where flow out of the well is diverted to an automated MPD choke manifold with a high-resolution mass flow meter that increases the sensitivity and reaction time of the system to kicks, losses and other unwanted drilling events. Experiments and field deployments have shown that the deepwater MPD system can detect a gas influx before it dissolves in oil-based mud, allowing for management of the same using conventional well control methods. Since the MPD system has already closed the well in, automatic diversion and control of gas in the riser is also possible, if required, thereby further minimizing the likelihood of an environmental discharge should a riser gas event occur. Experience gained from deepwater MPD operations in Asia Pacific will be presented to illustrate this.

The wells in Soka field in onshore South Sumatra, Indonesia are drilled through a fractured carbonate reservoir (Baturaja formation) where severe circulation losses and kicks while drilling are commonplace. Drilling in one of the wells in the field, Soka 2006–1 was suspended for two years due to total losses combined with gas kicks. Almost two months were spent after total loss of circulation was experienced trying to control and drill Soka 2006–1 to no avail. The well was plugged and abandoned on July 2006 with the intention of returning to it and finishing it once an appropriate approach can be developed to address the drilling issues that were encountered. The approach chosen for re-entry operations in Soka 2006–1 was a managed pressure drilling (MPD) technique called Pressurized Mud Cap Drilling (PMCD). A rotating control device (RCD) is the main component used in PMCD operations, the objective of which is to eliminate the non-productive time (NPT) associated with drilling when loss - kick scenarios occur. A new well, Soka 2006–6, was also planned to be drilled in the area using the same technique, but with the addition of a downhole isolation valve that was to be installed and cemented together with the last casing string above the section where losses are expected. The casing valve allows for safer and faster tripping operations and more importantly, can serve as a downhole lubricator that will help facilitate the running of the completion assembly in PMCD mode. A casing valve could not be installed in Soka 2006–1 as the casing string above the loss zone was already in place. This paper describes the planning and implementation of the PMCD technique in both the Soka 2006–1 and 2006–6 wells and discusses the results of the drilling operations. Furthermore, it explains how drilling in PMCD mode allowed re-entry operations in Soka 2006–1 to reach the target depth in less than a day after total loss of circulation was again experienced, and how the completion assembly was run and cemented in PMCD mode. Introduction The Soka Field is located on the Musi Platform of the South Sumatra Basin. Figure 1 shows the stratigraphy of the South Sumatera Basin. One of the wells to be drilled in the Soka field is Soka 2006–6. This well is proposed to reach the oil column at the Baturaja formation, and its main objective is the carbonate reef facies of the said formation. The well is designed to penetrate 681 feet of Baturaja limestone. Re-entry operations on another well, Soka D7 or 2006–1, is also planned to penetrate the Baturaja limestone by 371 feet, 95 feet of which consists of the oil column. Re-entry of Soka 2006–1 is intended to complete drilling operations on the well, which have been suspended for two years due to total circulation losses and accompanying gas kicks encountered while drilling in the upper section of the Baturaja Formation. Around one and a half months were spent after total loss of circulation was experienced trying to control and drill the original Soka 2006–1 well to no avail. It was plugged and abandoned on July 2006 with the intention of returning to it and finishing it once an appropriate approach was developed to address the drilling issues that were encountered. The utilization of the current Soka 2006–1 borehole for re-entry is intended to minimize drilling cost, since risk for drilling in Baturaja formation in this cluster is similar for other trajectories.