We present a study of static and dynamic interfacial properties of self-assembled polyelectrolyte complex nanoparticles (size 110-120 nm) containing entrapped surfactant molecules at a fluid/fluid interface. Surface tension vs time measurements of an aqueous solution of these polyelectrolyte complex nanoparticles (PCNs) show a concentration-dependent biphasic adsorption to the air/water interface while interfacial microrheology data show a concentration-dependent initial increase in the surface viscosity (up to 10(-7) N·m/s), followed by a sharp decrease (10(-9) N·m/s). Direct visualization of the air/water interface shows disappearance of particles from the interface over time. On the basis of these observations, we propose that the PCNs at fluid/fluid interfaces exist in two states: initial accumulation of PCNs at the air/water interface as nanoparticles, followed by interface induced disassembly of the accumulated PCNs into their components. The lack of change in particle size, charge, and viscosity of the bulk aqueous solution of PCNs with time indicates that this disintegration of the self-assembled PCNs is an interfacial phenomenon. Changes in energy encountered by the PCNs at the interface lead to instability of the self-assembled system and dissociation into its components. Such systems can be used for applications requiring directed delivery and triggered release of entrapped surfactants or macromolecules at fluid/fluid interfaces.

This paper presents a case history of a slickline propellant stimulation treatment performed in a well at the Penara and North Lukut field, which is a small oil field operated by PETRONAS Carigali offshore Peninsular Malaysia. The stimulation was performed using propellant that rapidly burns to create a high pressure gas pulse, which in turn breaks through damage in the perforation tunnels and near wellbore, effectively creating fractures through the damaged zone to enhance well productivity. The Penara and North Lukut reservoir pressure is around 3000psi with a bottom hole temperature of 258oF. The Crude has a medium gravity of 32 API, however it has a low GOR and high wax content with a tendency for heavy wax deposition. Frequent scraper runs are required to prevent excessive wax deposition in the low rate wells which have well head flowing temperatures below the wax cloud point temperature. Nowadays, slickline, due to its light weight, is widely used to perform well interventions and perforating operations on small platforms. Conventional CTU and E-line are often too heavy to be lifted on board by the platform cranes. Since field production start up in August 2004, slickline has been successfully used for well interventions to change out gas lift valves and to carry out regular tubing wax scraper runs. Slickline with 0.108"stainless steel wire was used to convey the propellant stimulation guns. Propellant simulation software was used to simulate the downhole pressure response to ensure that well integrity would not be compromised and to help select the optimum gun size. For each treatment one 10 foot, 2 inch OD gun was used. An additional unique feature of the tool string was the gun firing mechanism which utilized a coded sequence created from variation of surface jerking rate to generate its firing command, providing reliable and safe gun activation. Lastly, this paper also details the results of the propellant stimulation treatment which significantly enhanced the productivity of the treated well. Introduction The Penara and North Lukut field is located in the northeastern fringe of the Malay Basin in South East Asia, approximately 300 km offshore Terengganu, Malaysia in a water depth of 62 m and at the time of development was considered to be a marginal field. The field has been developed using two monopod platforms, one at Penara and one at North Lukud, both of a lightweight structural design (Figure 1) featuring an integrated deck and topsides concept connected via sub-sea pipelines to a Floating Production, Storage and Offloading (FPSO) vessel. The Penara reservoirs are of early miocene age deposited under fluvial environment with meandering stacked channel systems. The sands exhibit a fining upwards sequence of multiple stacked channels sands. The Penara well was initially drilled to target the I-65 oil sands. I-65 was however found to be wet with the well sidetracked twice. The two initial pilot holes were eventually plugged back and the well was completed with 3 ½ inch tubing as a single selective oil producer in 4 zones K-5, K-10, K-20.5 and K-50.1. (Figure 2) Based on open-hole logs obtained from Logging While Drilling operations, K-20.5 is an argillaceous sand with significant amounts of silt and clay content. It has a net to gross of 0.47 and a net pay of 7.3 m with average Sw of 47.18% and average porosity of 12.48%. The K-50.1 is a better quality reservoir with some silt and clay streaks. The net to gross is 0.92 while the total net pay is 20.3 m with average Sw of 56.42% and average porosity of 15.42%. K-20.5 and K-50.1 are separated by a shale break.

Brownfield in Balingian and Baram Delta have handful of idle wells and well to be abandoned in their inventories. The project aims to reduce the idle well inventories and support production gain through monetizing behind casing opportunities. The target is to appraise and develop LRLC potentials with lower cost of appraisals. This will maximize full field potentials before abandonment and leads to future development of LRLC opportunities as conventional reservoir becomes more difficult to develop. The idle well inventory has grew up due to problem in production (increase water cut, HGOR) and well problems (sand, fish). An order has been introduced to reduce the idle well list up to 50%. Additionally, in the past, the LRLC intervals were often ignored and considered as water-wet sands due to high water saturation or as tight sands. These intervals, that contain significant reserves, are recognized in many technical papers explaining its identification and evaluation techniques from well-data (logs and samples/cores). The scope of the project is to rejuvenate the idle wells by add-perf LRLC reservoirs. It is impossible to achieve the target without the presence of proper and improved LRLC BCO evaluation process, thus an integrated workflow approach (between Petrophysicist, Reservoir Engineer, Production Technologist, Asset manager & Well Intervention group) has been developed and applied in the project. A new evaluation tools had also been developed called REM (Resolution Enhanced Modelling) in order to improve the log properties of LRLC reservoirs so that the data obtained from old conventional tools can still be used to evaluate LRLC reservoir. Although LRLC is termed UNSEEN, the risk is reduced by proper understanding of hydrocarbon column and sand development. To date, 7 fields are already benefitted from this approach. Field A LRLC reservoir for example has tripled the hydrocarbon saturation, and net to gross has improved to 20% using REM compare to 5% without REM. The other 6 fields are also gaining the same increase in the properties. This has resulted in a cumulative potential of 4.4 MMstb of reserves addition and ~11 KBopd potential gain. As a result, a better and attractive BCO proposals can be generated from LRLC opportunities. The exercise will provide the company with cheaper options of appraising and developing LRLC reservoir while reducing the idle wells. There is no better way of understanding LRLC reservoir; as no tools can identify & quantify it yet, rather from the actual production.

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