The SB Field is located in Block PM on the west side of the Malay Basin, Malaysia. It is notorious for its steeply rising pressure ramp, narrow drilling operation window and inter-bedded sand, coal, and shale formations. Block PM is still at the exploration and appraisal stage with limited petrophysical information. Well SBD-2 was the second attempt to reach and cross the F & H sands of this basin. Despite using managed pressure drilling, the first attempt failed when an influx exceeded the fracture gradient, resulting in total fluid losses. Due to the shallow pressure ramp and narrow window between pore pressure and fracture gradient, a repeat attempt was initially deemed "un-drillable". However, the design team felt the target could be reached using an automated managed pressure drilling technology. The team was able to maintain constant bottom hole pressure over three demanding hole sections and reach target total depth. The 8-1/2" × 14-3/4" section required minimum overbalance to manage "wellbore breathing" and to control potential losses to weaker horizons. In the 10-1/2" × 12-1/4" section, the system was used to identify and react quickly to kicks in high pressure sands and also to eliminate wellbore breathing/ballooning. In the final 8-1/2" × 9-1/2" section, the objective was to maintain overbalance in the narrow pressure window between pore pressure and fracture gradient. This paper will describe the design efforts employed while preparing to drill the SBD-2 well. The challenges and lessons learned, particularly managing pore pressure prediction with multiple techniques will be discussed. Lessons learned and recommended workflows for similar projects will also be outlined.

Using a Dynamic Hydraulic and Well Control Simulator to predict and establish wellbore pressures in a narrow margin HPHT well has allowed the operator to set operational limits during drilling, tripping, casing and cementing operations. A previous attempt to reach the objectives for the well failed. A much more rigorous approach to wellbore pressure management was undertaken prior to drilling this second well. A complete review of the expected pressure limitations was conducted, this review included a detailed overview of pore and fracture pressures as well as casing setting depths, hole sizes, temperature effects and proposed mud weights. This resulted in an improved prediction of the pressure windows for each of the proposed hole sections. Each hole section was in turn reviewed for optimal mud weights and this included a detailed review of equivalent static, equivalent circulating and dynamic kick tolerance limitations for the proposed mud weights. Surge and Swab calculations then determined maximum tripping speeds and cementing calculations ensured that pore and fracture pressure limits were not breached with the proposed cement volumes and pump schedules. This paper presents the approach that was taken in proving a complete pressure management system for a narrow margin HPHT exploration well. The use of dynamic hydraulic models allowed accurate predictions of down hole pressures during virtually all drilling operational phases a hole section. Calculated down hole pressures were compared to PWD tools, proving that the accuracy of the dynamic hydraulic predictions was within the required limits to allow drilling without a PWD tool if required. Combining the available pore pressure and fracture pressure data, with mud weight schedules, pump rates, tripping rates and cementing operations allowed optimization of the drilling parameters thus ensuring that this narrow margin HPHT well, was drilled successfully to its target depth and all of its objectives were met.

Enhanced Magnetic surveying technique was introduced to Field Q in Malaysia allowing the tight geological target requirements to be achieved without impacting the operator’s drive for drilling efficiency. Managing wellbore uncertainty is a significant challenge in Field Q, West Malaysia, where the Subsurface Team defines tight reservoir targets to accommodate the uncertainties that they have in a long step out well. Accurate well positioning becomes crucial in this situation to allow the penetration of multiple small targets. Historical approaches would have involved either running gyro surveys (which introduce more risk and time to the drilling process), or having to "over engineer" the wells (by creating tortuous well paths and drilling on the line to achieve the small drilling targets) due to the uncertainties of standard MWD surveys. Both of these approaches are against the drive to continually improve drilling efficiency while reducing risks. Magnetic surveying has become increasingly accurate and now provides a cost-effective alternative to gyroscopic surveys in real-time drilling applications. New techniques for identifying and compensating for these errors involve a better understanding of the natural variations in the earth’s magnetic field, and new methods of mapping local variations improve magnetic modeling. The enhancement involves a multi-station analysis technique that provides compensation for drillstring magnetic interference and further improved when used in conjunction with geomagnetic referencing, which takes account of localized crustal effects in the earth’s magnetic field. With a Geomagnetic Referencing System in Field Q, magnetic survey reduced uncertainty by 60% on average compared to a standard MWD error model. The benefits from this real-time drilling surveying process also means drilling is more accurate, with a reduced need for correction runs, or post-drilling changes to the planned well trajectory.

Wells drilled into gas bearing carbonate reservoirs in offshore Sarawak are prone to severe lost circulation issues. In the first 3 exploration wells, total losses were encountered after drilling 20 m into the carbonate in 8.5-in. hole section. The well managed to drill to TD with application of pressurized mud-cap drilling. However the challenge of the total losses wellbore is the incomplete cementing of the 7-in. liner across the carbonate column. Poor zonal isolation and reduction of reservoir permeability were major concerns to the operator requiring significant investigation, laboratory testing and pre-job planning for future wells. This paper will discuss an unique design technique for curing the challenging lost circulation issues while also providing improved cement placement along the fractured formation. Lab test results are presented using a bridging material simulator with different fracture sizes to evaluate the sealing effectiveness of the engineered systems. Return permeability studies using a Hasseler-style core holder were conducted for the fluids to verify their damage potential to the producing formations.The engineered solution was the use of a cement spacer fluid containing membrane forming colloids to seal fracture sizes up to 2 mm which also yielded 100% return permeability to hydrocarbons. The use of the spacer fluid enabled successful cement placement along the critical carbonate section. A bond log evaluation showed that there was cement coverage along the zones of interest. Based on the positive lab tests and field results, the combination of a sealing spacer and lightweight cementing system was identified as a viable solution to combat lost circulation and improve cement placement for future wells drilled in this area.

The HPHT Exploration field is located in Block PM on the Northern side of the Malay Basin, Malaysia, and is notorious for its steeply rising pressure ramp, narrow drilling operation window with only 0.5ppg-0.6ppg in the 14-3/4" and 9-1/2" sections and inter-bedded sand/coal and shale formations Block PM is still at the exploration and appraisal stage and therefore there is limited petrophysical information. Well SBD-2 was the second attempt to reach and cross the F & H sands of this basin. This paper will detail how Formation Pressure While Drilling (FPWD) and Managed Pressure Drilling (MPD) were successfully applied to drill this HPHT exploration well with a very narrow safe mud weight window. FPWD provided a direct pressure measurement while drilling to set the lower boundary and the Dynamic Formation Integrity Tests (FIT) with MPD provided the upper boundary.All the benefits of using a fully automated managed pressure drilling system were necessary to reach Well TD for the first time in this field; including Early Kick Detection (EKD), Dynamic Formation Integrity Tests (FIT), Dynamic Flow Checks and Constant BHP control within a narrow pressure margin.The result of the combined technologies and operational procedures is safely drilling the first successful HPHT well in Malaysia drilled with MPD constant bottomhole pressure application. This well is so far the deepest gas discovery for the north Malay Basin.