Uncontrolled sand production has caused serious complication and monetary loss in oil and gas assets worldwide especially in mature fields. It is known to be drastically limiting the production rates and damaging downhole and surface equipment, inducing the risk of catastrophic failure. Sand production is commonly associated with contributing factors such as unconsolidated formation, initiation of water breakthrough and changes in rock stresses due to depleted reservoir pressure. To mitigate sand production, operators often opt for applying mechanical or chemical downhole sand control methods. This paper will discuss about the performance results and lessons learnt from the application of chemical treatment for downhole sand control over several mature fields in Malaysia. Chemical sand consolidation (SCON) and sand agglomeration have been identified as effective chemical treatment to control sand production downhole. Both treatments involve injection of chemical into immediate near wellbore area of the reservoir with the aim to improve the strength of the incompetent formation and thus reducing the tendency for sand production. In most cases, SCON treatment consists of injecting fluid containing adhesive or resin for binding the sand grains while the main mechanism of sand agglomeration involves increasing the attraction between sand particles through processes such as polymer bridging interactions and charge neutralization. Stringent candidate screening and detailed pre-job planning are crucial in ensuring the success of both SCON and sand agglomeration treatment. Over the past few decades, there were about 20 SCON treatment jobs and 3 sand agglomeration jobs were performed across several Malaysia fields with varying service providers and chemicals. The overall success rates for sand consolidation and sand agglomeration are 75% and 66% respectively. To evaluate the effectiveness of the chemical treatment for downhole sand control, analysis was conducted to study the effects of parameters such as completion type, perforation length, formation permeability, clay content, well preparation, formation temperature and placement methods. This paper presents lesson leamt and best practice from several chemical SCON and sand agglomeration treatments performed over mature fields in Malaysia. Case studies for several wells will be examined to highlight the lesson learnt which are essential to further enhance the success of chemical SCON and agglomeration treatment. Best practice shall be incorporated into future campaigns to ensure chemical treatment as a successful means to control sand production downhole in a low-cost environment.
Low oil prices, coupled with operational challenges in offshore environment due to COVID-19 restrictions, have driven oil and gas operators to implement low-cost technological solutions to optimize fields’ production. For mature oil fields in offshore East Malaysia, sand production has become one of the onerous challenges that requires this approach. Sand production is known to adversely affect the well deliverability and it also contributes to safety concerns due to surface flowline leak and equipment failure. Hence, it is of upmost importance for operators to address the sand production downhole. To achieve this, through-tubing sand screens (TTSS) installation is opted due to its ease of installation and low-cost slickline operation. Although there have been many TTSS installations to date, there is still limited understanding of the factors that affect TTSS lifespan, and this has led to frequent TTSS changeout. Based on the operator's experience, TTSS lifespan can vary significantly across different wells ranging from just a few days to years of production. To improve the understanding of TTSS performance with the aim to increase TTSS longevity, a comprehensive study on potential contributing factors has been conducted by analyzing the past TTSS installations. Over the years, there were more than 75 TTSS installations performed in oil fields offshore East Malaysia. Lookback analysis was conducted to evaluate the effectiveness of TTSS as remedial downhole sand control and investigate the factors affecting TTSS performance such as TTSS type, well production rates, TTSS deployment method, installation depth relative to perforation interval and well interruption frequency. Several criteria identified as the key performance indicators have been investigated to evaluate the performance of each TTSS installation, including the well flowing parameters, production uptime and sand production trend. Thorough study across different TTSS installations has concluded that TTSS lifespan varies according to well properties and well operating parameters. This paper presents best practices and lessons learnt from past installations to predict and improve the mean time between failures (MTBF) for TTSS. Case studies for several wells have been scrutinized to highlight the learnings for further enhancement of TTSS lifespan. Additionally, recommendations for further research and development of erosion resistant TTSS technology are also discussed.
Formation sand production is one of the major production challenges in most of the mature fields in Malaysia. Often, failure in primary sand control equipment requires the operators to adopt through-tubing sand screens as remedial sand control. Due to the erosion prone nature of the thru-tubing metallic sand screen, operators are forced to impose limitation on the production rate coupled with stringent surface sand monitoring system to avoid surface flow line leakage and loss of primary pressure containment. Therefore, to seek a more robust technology than conventional metallic screens, alternative technology with through-tubing ceramic sand screen (TTCSS) has been considered with the idea of higher durability and resistance against erosion. This paper will discuss the performance and lessons learnt from the application of through-tubing ceramic sand screen throughout several mature fields in Offshore East Malaysia. Over the past two years, there have been about twenty-five TTCSS installations in Offshore East Malaysia. Seven pre-mature failure cases were observed, where sands were produced to the surface and even caused leaks on the flow line. The average effective production period for all TTCSS across all the fields ranges from 6 to 11 months. Teardown investigations have been conducted to diagnose the failure root cause. Most failed TTCSS exhibited similar failure patterns at the end caps, which house the spring compensator. Failure to stop the flow through the end caps led to substantial erosion at spring compensator and base pipe, inducing large flow path for sand production to the surface. Other than the design failure, application failure was observed at the ceramic rings due to their brittleness. Computational fluid dynamic simulation and laboratory testing have been conducted at the higher incremental production rates to support the observations from teardown inspections, refine the hypothesis of failure mechanism and enable an incremental design change to be modified into TTCSS. In order for TTCSS to be one of the competent candidates for remedial sand control, new improved standard design of TTCSS with strengthened end cap area will be studied to prevent similar failure.
In the oil and gas industry, operators strive to minimize loss time and production while keeping its facilities and operations safe. Over the past few decades, technological innovation has equipped the industry with the equipment and practices necessary to make the exploration and production more efficient, safe and environmental friendly. This paper discusses successful implementation of several non-intrusive technologies by the operator for redevelopment of maturing oilfield in offshore East Malaysia. The field was discovered in 1967 and oil has been produced since 1972 from the major hydrocarbon accumulation in 8 producing reservoirs, sandwiched between shallow gas-bearing reservoirs and deeper gas/condensate-bearing reservoirs. Enhanced Oil Recovery (EOR) redevelopment project in the field began in 2018, targeting the major oil reservoirs and Non-Associated Gas (NAG) reservoirs. Crestal gas injection and flank water injection will be implemented to further develop the oil rims of A and B reservoir while Immiscible Water-Alternate-Gas (IWAG) injection will be implemented in the C reservoir. The EOR scheme will include infill drilling of new wells and workover of existing wells to deliver targeted incremental oil recovery. The journey towards EOR redevelopment project consistently requires integrated contributions from multiple disciplines such as Petroleum Engineering, Production, Well Services, Facilities and Process Engineering, which has been facilitated effectively through Reservoir, Well and Facility Management (RWFM). This holistic work process involves creating critical strategy for EOR redevelopment activities, optimization decisions and asset management, ensuring the delivery of remaining reserves and long-term production maximization. By implementing RWFM collaboration and support, several non-intrusive technologies have been evaluated & implemented to solve long overdue problems such as online acoustic sand monitoring system, non-intrusive acoustic valve inspection device and active sonar meter. Overall, this paper highlights the working principles, actual field results and lessons learnt from the application of non-intrusive technologies through RWFM collaboration that deliver significant cost and efficiency benefits as well as safety for prudent brown field EOR redevelopment.
Managing sand production has been a common problem and one of the most difficult challenges within the oil and gas industry. Various techniques are available to control sand production such as downhole sand screens. More than half of the wells in Malaysian fields are completed with downhole primary sand control or require sand management throughout their lifetime. To further aggravate the issue, most primary sand controls installed have suffered from failure after an extended period of production due to unacceptable high pressure drop in the near wellbore area which causes the screen to lose the ability to retain the formation sand particles. There are four (4) common mechanisms that can lead to the screen failure which include plugging, corrosion, erosion, and mechanical deformation. Erosion occurs when the formation particles hit the screen surface with high velocity or by continuous production through the screen openings. Operators are often compelled to rely on thru-tubing metallic sand screen to reactivate the idle wells back into production. However, most metallic sand screens suffer from sustainability issue due to excessive erosion especially for gas wells. Most operators have shifted their focus to maximize the screen lifetime against erosion, which consequently leads to the development of a novel sand screen design where an inventive coating consists of ceramic or hard metal amalgamation was applied by plasma spraying technique on the screen (i.e., outside surfaces facing the formation) to reinforce its resistance against severe erosive environment. An extensive development and verification program was conducted to select over 50 possible coating combinations, guarantee predefined slot size, assess corrosion resistance, and ascertain mechanical integrity of both the coating and screen. The technology has been considered and applied in Field A, offshore Borneo Island as remedial sand control due to its superior durability and resistance compared to metallic sand screen. Extensive technology hunting had been conducted by the operator to identify new erosion resistant thru-tubing sand screen for gas well application. As part of the overall project requirement, test facility was built by the Service Partners that consists of a flow loop testing designed to simulate accelerated erosive downhole condition with the combination of high flowrate and volume-controlled particle coalesced into an acceleration tube. The screens were tested for 60 hours at maximum velocity of 18 m/s during liquid erosion test and for 48 hours at maximum velocity of 80 m/s during gas erosion test. Rigorous analysis was conducted focusing on among others optical criteria, mass loss and sand retention tests (SRT) before and after the erosion test to verify the functionality and validate its performance prediction prior to the actual field application. Velocity calculation was also conducted using in-house and commercial software to adjudicate the design limit, to set the target gas rate for the pilot wells and establish the well unloading procedure as guidance for offshore personnel. Pilot field trials have been designed to demonstrate screen installation, risk mitigation and sustained production. Dual-pot sand filter (DPSF) and online sand sampler (OSS) was deployed as additional assurances to safeguard topside integrity, to closely monitor the sand production at surface and collect any sand grains larger than the screen slot sizing throughout the well unloading sequence. Close inspection on both erosion tests indicated no significant wear or slot size widening of the coated screen samples as compared to the uncoated screen samples that show severe erosion with slot size increases more than doubled in some places. The coated screen samples show the equivalent sand retention capabilities before and after the erosion tests, while the uncoated screen sample subjected under the same conditions lost its ability to retain sand. During field trial, the screen was successfully installed using nipples plug via slickline to revive the idle wells back to production at a lower total cost without HSE related issue and production gain beyond the initial target. Actual field results supported by the extensive laboratory testing presented herein, demonstrate the inherent benefit of plasma spray coatings ensuring mechanical integrity and durability of sand screen in highly erosive environment. Teardown analysis will be conducted to investigate the performance prediction, authenticate erosion resistance of the sand screen bottomhole assemblies (BHA) and document the findings for future improvement.
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