Objectives/Scope Perforate, Wash & Cement (PWC) is a method developed over the past decade to help increase efficiency in plugging & abandonment of wells. The method has helped operators world-wide to save time and cost in plugging and abandonment operations by cutting down time for setting full lateral barriers. This technique can also be used to set permanent lateral barriers for slot recovery operations, and perform well repairs on workovers where there is sustained casing pressure. The technology is used to set lateral barriers to cure the sustained casing pressure, and enable the operator to put the wells back into production. The integrity of the well is restored and significant value is generated. However the technology has previously been limited to setting one barrier at the time. The unique challenge for this well on the Platform Alpha, offshore Malaysia was that two zones had to be isolated in one run. The distance between the two zones was almost 100 meters. A significant challenge, with a significant upside. The execution was using Hydraulic Workover Unit (HWU) and overall 14 plugs completed (for 14 wells). Methods, Procedures, Process The method has several critical success factors that need to be tailored to be able to produce a high quality result, especially with this unique challenge of plugging and abandoning two different zones in the same run. Optimization of the Tubing Conveyed Perforation (TCP) System to be able to balance hole size, geometry and density in order to create the ideal communication path into the external annulus was paramount to the success of the job. The TCP needed to also take into consideration casing size, weight and metallurgy to ensure that downhole conditions are simulated as accurate as possible, increasing the chance of successfully meeting the perforation criteria that has been optimized. Washing parameters needed to be optimized to be able to create high annular velocity for efficient hole cleaning and debris removal. This optimization takes into consideration the fluids density and rheology, ensuring that the mud system has the correct properties to suspend the debris for removal at surface. The compatibility and stability of the fluids and mud condition prior to cementing operation is also critical. The cementing operation on this well was a unique, tailor-fit engineering project, with the end goal and intention of being able to isolate two zones approximately 100 meters apart at the same time. The cement & spacer properties were important here due to possible gas, and high chance of losses into the formation after perforating, and during washing. The volumes, operational parameters and execution were critical to get the two zones efficiently plugged and abandoned in one run. This paper describes the extensive work that has been performed to plan and execute the successful plugging and abandonment of two independent zones using the Perforate, Wash and Cement technology; and in the process, saving several days of rig time, gaining significant value for the customer and setting a new benchmark for efficient plug and abandonment operations for the global market. Results, Observations, Conclusions The system testing of the TCP Gun system resulted in an optimum Exit Hole Diameter (EHD) and exit hole geometry tailored for this specific wellbore size, weight and metallurgy. The washing was efficiently carried out with high amounts of debris over the shaker system and a declining standpipe pressure was observed indicating a very successful washing of the perforations. The cement operation was flawlessly executed according to the planned operational parameters with no losses or operational challenges. The two zones were effectively isolated in 2.5 days. This fantastic result not only significantly lifted the efficiency of the Platform Alpha Plug & Abandonment operations, but also set a new benchmark for the Perforate Wash and Cement Technology globally. By isolating two independent zones in one run using the Perforate Wash and Cement Method, the technology has proven that within an already established methodology, there is still capacity for further progression and evolution of the technology. A one team effort between operator and service companies made this possible and in the process, established a solid blueprint for future efficient, safe and reliable operations.

This paper focuses on the application of pre-stack seismic inversion to delineate gas reservoirs for development well targeting of the Muda Field in the Malay Basin. A comprehensive development well targeting workflow was established to integrate information from all related disciplines and convert them into an optimized well design. One of the key tasks in this workflow was to select an appropriate seismic attribute to identify the distribution of reservoir sands in this area. These reservoirs are generally characterized by thin sands inter-bedded with coals. Relative Poisson's Ratio (RPR) was used to identify reservoir targets prior to development drilling. Drilling results later indicated that a high proportion of the proposed anomalies (87%) correspond to gas sands. The remaining (13%) are related to highly saturated sands, Additional Zones of Interest (AZIs) or shale. Preliminary results therefore demonstrate that the RPR attribute can be used as an effective tool in development well targeting.

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Low electrical resistivity and low contrast reservoirs (LRLC) pay zones are composed of thinly-bedded laminated layers containing hydrocarbon accumulations surrounded by non-reservoir layers indicating lack of resistivity contrast. These pay zones are difficult to be distinguished at seismic and log scale due to lower vertical and lateral resolution. Traditionally, deep-resistivity logs in LRLC zones read 0.5 to 5 ohm-m. Low contrast pay zone occurs mainly when the formation waters are fresh or having low salinity resulting in a very little resistivity contrast between oil and water zones. Major challenges imposed in LRLC reservoirs include identification, characterization, and evaluation of the hydrocarbon interval, which is usually masked by the lack of resistivity contrast between the hydrocarbon and water zones. The identification and characterization of the lowdown on resistivity pay is essential for the re-development of mature assets for improved oil recovery. This paper deals with the characterization of low resistivity hydrocarbon-bearing thinly-bedded reservoirs from a brownfield. To unlock the hidden potential of LRLC pay sands in the offshore Sarawak Malaysia, the effective integration of subsurface disciplines including petrophysics, geology and quantitative derivatives from the seismic analysis is vital. This study covers the geological perspective of low contrast reservoirs from an offshore oil field deposited in lower coastal plain settings located within offshore Sarawak Malaysia. An improved understanding of the geological, petrophysical and geophysical parameters was achieved by adopting a holistic and multidisciplinary approach. This includes the integration of core, logs, rock physics modeled parameters, stratigraphic, depositional and lithofacies information along with stochastic inversion derivatives. Acoustic Impedance shows the facies changes in broader terms between producing and non-producing zone. The paper quantifies rock physics parameter uncertainties for LRLC pay zones and establishes a framework for LRLC reservoir characterization. Stochastic inversion derived P-Impedance and Vp/Vs ratio are used to predict fluid and facies probabilities (Rajput S., 2014) for LRLC reservoirs, which then further integrated with stratigraphic information. The results offered an effective way of establishing analogs of producing and non-producing LRLC zones. Analysis of fluid and facies probabilities derivatives driven surface attributes is a way seismic can potentially contribute to indicating areas of relatively better or worse LRLC reservoir continuity. Identified LRLC reservoirs proved to be of commercial-quality and increased oil production to the extent of several hundred thousands of barrels over the years and currently producing. Rock physics modeled parameters including AI and Vp/Vs are sensitive to LRLC pay zones and their effective integration with image logs, lithofacies, and seismic inversion lead to reduce uncertainties in infill drilling programs. Geological understanding of the possibility of LRLC occurrences is required to assess oil and gas bypassed oil. Detailed geological features are clearly resolved in high-definition image logs. Low resistivity pay zones present in the main reservoir intervals can be identified by integrating the information from low gamma ray, low impedance, and low resistivity zones collectively. The results of this study show the value of integrated approaches and improvements in reservoir description from stochastic inversion into reservoir models.

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