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Numerous perforation jobs are performed daily around the globe on a routine basis to establish wellbore to reservoir communication. However, in some cases, these perforating operations can result in poor well productivity or severe health, safety, security, and environment (HSSE) incidents. In this paper, the key elements of proper perforating operations, from data gathering to design and safest possible execution, are summarized to create practical guidelines for operators. Oil and gas wells are drilled, cased, cemented, and perforated as a result of diligently planned multidisciplinary engineering work. The engineers have traditionally designed perforations to have cleaner, larger, and deeper tunnels into reservoir rock to enhance the communication quality between the wellbore and reservoir. Research has proved that wellbore dynamics have significant control on the success of perforating activities during this fast-paced and short-lived event. Therefore, recently the trend has evolved from static underbalanced perforating to dynamic underbalanced perforating via advanced downhole gun system designs and downhole tools. Conventionally, operators have focused on debris and damaged rock removal from the perforation tunnels by applying static underbalanced perforating. However, static underbalance alone does not guarantee the optimal perforation tunnel structure. Research has shown that dynamic underbalance can significantly enhance tunnel cleanup and well productivity. Today, numerical perforating dynamics software is available to simulate wellbore dynamics for a given perforating design with various downhole tools. Perforating gun detonation pressures and the resulting shock waves can damage downhole tools and hinder wellbore integrity if not mitigated properly. In Oman, carefully designed and executed perforating operations have improved well productivity and operational safety for many years. Each perforating job is assiduously planned and executed. Specially designed software packages are used to simulate the wellbore conditions and downhole equipment response to identify and mitigate potential problems and to improve the efficiency of perforating tunnels cleanup prior to each perforating job. The application of this methodology has resulted in performing numerous highly successful perforating jobs in Oman. The results of these perforating jobs are presented here as case studies. The static and dynamic wellbore conditions as simulated and observed during the operations with a fast downhole gauge are compared and discussed in detail. Lessons learned and guidelines are presented in an easy-to-follow way to help operators achieve successful results. The methodologies and best practices outlined in this paper enable improved perforation designs by using available software in challenging environments where conventional approaches can be inadequate. The methodology is described systematically in detail so that the procedure and learnings from Oman's hydrocarbon producing wells and reservoirs can be adapted to other operations around the globe.

The acquisition of downhole pressure data representative of reservoir response enabling subsequent pressure transient analysis has been one of the primary drivers for running drill stem tests. However, many factors can influence the representativity and interpretability of the data acquired that are not related to reservoir properties. To our knowledge, while many publications have presented challenges in acquiring representative pressure data those have not been compiled in a comprehensive revies, and there are no practical recommendations that would summarise causes and effects and offer procedures to eliminate or at least manage those effects and enable end-users to maximize the value of acquired data. This paper describes in details today's challenges associated with the acquisition of high-quality, representative and undisturbed bottom hole pressure data during well test operations. Many different effects, including gauges’ deployment methods, wellbore effects and operational aspects of the test can compromise the quality of bottom hole data acquired while running a welltest. Therefore, the origin and impact of each of these effects needs to be evaluated at the design stage of the test to develop appropriate mitigation actions. To address these issues, actual examples and methodologies derived from various locations are presented. Over the years the metrological performances of downhole memory gauges such as resolution or drift have improved drastically, reaching a point where gauge specifications have become less influential on data quality than environmental effects. Many improvements have also been made in DST tools to increase the representativity and interpretability of acquired bottom hole pressure data such as the introduction of downhole shut-in valves or compensation for tubing contraction and expansion due to temperature change during the test. However, there remain several occurrences today where memory gauge data are affected by the various wellbore phenomena making interpretation of downhole pressure transient test data complicated. The selection of an appropriate location of pressure sensors in the DST string also remains a crucial task. The paper provides analysis, explanations and practical recommendations allowing to mitigate the most common effects typically observed during welltest operations performed around the world, such as:–Tidal effect–Fluid segregation effect in the wellbore–Pressure noise propagation from the surface due to rig movement–The impact of application of electrical submersible pump (ESP) on the quality of pressure build-up data–"Hammer effects" during well shut-in–Impact of circulation above the test valve during PBU–Impact of pressure bleed off and top up in the annulus–Fluid cooling effect in the wellbore–Gauge movement due to string contraction and expansion This paper will summarise the observation and lessons learned from hundreds of welltest operations performed around the globe with different reservoir fluids and environments through a few telling examples. Furthermore, the paper provides practically proven well-test techniques allowing to manage those adverse effects on bottom-hole pressure data. Recipes for success are provided to ensure that high-quality data can be acquired during welltest operations in a challenging environment while keeping the cost in line with the AFEs.

Pressure transient testing has been significantly revamped and various types have been applied for numerous motives over the past decades. In this paper, a methodology and adapted technology have been discussed in detail for enabling downhole testing operations with existing open perforations above the test packer. This methodology enabled successful downhole testing operations where conventional annulus hydraulic pressure pulse system was ruled out for numerous reasons, such as existence of perforated zones above zone of interest and/or well integrity constraints. The proposed method is based on an acoustic, wireless, bi-directional downhole to surface communication telemetry system. The process utilizes acoustic signals to control downhole tools and transmits downhole measurements in real time through a secured network connection. The procedure used in this well testing methodology is proven successful in numerous well test operations for exploration and appraisal wells in Algeria. The continuously unfolding downhole data has enabled end users and stake holders to take actions and decisions that maximized the value gain while optimizing the test durations and drilling rig utilizations. The successful application of this proposed methodology has enabled parameter estimation during the execution phase of the well testing operations. Data measured in real time is coupled with reservoir engineering interpretation to ensure meaningful sub-surface evaluation. Wellbore dynamics and several other inherent noise sources have been successfully identified to avoid snags of misinterpretation. Wells needing stimulation treatment or longer clean-up durations to enhance the well to reservoir communication quality have been handily identified in real time. The methodology has proven hydrocarbon existence in unexplored layers while enabling incorporation of additional test objectives with further assessments of zones of interest. Real time data greatly reduced uncertainties in well behavior and assisted in informed-decision-making process to adapt well test programs in real time. All well testing objectives were achieved by addressing various challenges that are inherent to conventional memory mode downhole testing operations. The methodology presented will enable the downhole testing operations through drill stem testing (DST) in complex wellbore geometries where conventional well testing approaches were rendered unattainable. The proposed solutions will warrant downhole testing of previously un-appraised formation layers that are overlain by perforated producing reservoirs. The methodology is described in detail and systematically so that the procedure and learnings from Algerian hydrocarbon producing basins can be adapted and applied to other well tests elsewhere around the globe.