The shape factor that appears in dual-porosity models of single-phase flow in naturally fractured reservoirs is investigated. Previously derived analytical expressions for a few simple geometries (spheres, cubes, slabs, etc.) are first reviewed. A general numerical procedure is presented that allows the shape factor of an arbitrarily shaped block to be found using a fine-grid simulation of flow into a single matrix block with constant-pressure boundary conditions. From these various results, a scaling law is suggested that expresses the shape factor in terms of the block's volume V, the block's outer surface area S, and a diffusion length l. This expression is α = 5S/Vγ, where γ = V 1/3 for a three-dimensional block, and γ = A 1/2 for a twodimensional prismatic block with cross-sectional area A. For all cases analyzed, this expression predicts the shape factor within an error of less than 10%. This seems to be the first accurate, general expression available for estimating the shape factors of irregularly shaped matrix blocks such as are formed by the intersection of realistic fracture networks.

Typical sand-control treatments applied in this field are high-rate water packs (HRWPs) or fracture for placement of proppant (FPP). In many cases, the use of a pad is necessary to maximize the amount of proppant placed into the formation and help reduce (bypass) overall skin using onsite data analysis. The gravel pack carrier fluid is a viscosified system with shear-thinning rheological properties and efficiently suspends sand in static conditions. Additionally, this fluid allows substantial flexibility in sand control design for varying degrees of sand support for gravel packing, fluid-loss control, friction-pressure reduction, and a low-damage fluid system (validated with extensive laboratory testing using reservoir cores with carrier fluid to validate returned permeability values). The objective of the relative permeability modifier (RPM) in sand-control chemical treatments is to prolong hydrocarbon production over time with effective control of water production in one step as a prepad fluid, eliminating the cost and complexity of the water-shutoff treatment stage later as part of well life. Applying the RPM process has not only reduced water production in these areas, but it has also resulted in more gas cumulative production. It is also important to monitor production for several months after the treatment to determine the success or failure of the application. Globally, this is the first successful application of RPM delivery in the same aqueous gravel-packing carrier fluid system using a pad fluid consisting of high-grade xanthan polymer as a gelling agent. Implementation of this process provides the operator an additional tool to increase the possibility of hydrocarbon production from a reservoir that has not been considered viable. Use of RPM technique in sand-control completions provides the option to treat wells and control water production resulting from nearby GWC after sand-control treatments.

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The ultimate goal of sand control design in producing hydrocarbons is to obtain solids free at lowest cost per barrel. Therefore, predictable production and its associated cost is vital to achieve the best business value. Previously, the prediction of production from sand control well is cumbersome. This paper presents the novel method which using the field data to provide the insight of sand control and deliver an optimal design for the sanding propensity well. Gravel pack sand control designs involves many parameters and is a tedious process for an engineer to interact with several dynamics parameters. This novel method started with field data collection from previous sand control operations. The datasets are prepared into the structured form, then reservoirs are sorted based on their similarities and finally the parameters are selected based on their significance. These parameters are mapped onto the productivity index using a variety of modeling types. The prediction result show that the productivity index can be modeled with high statistic measure (i.e. R-squared). Ultimately, Net Present Value (NPV) derived from anticipated reserves are known before pumping the gravel pack job. The continuous improvement of datasets can significantly help improve the sand control design. In this study, the novel method is presented using field dataset to optimize the sand control design. The design process can be driven with the use of data and machine-learning algorithms. This emerging technology allows greater insight into the day-to-day operations. The continuous adoption of this technology is a key enabler of futuristic industrial 4.0. The data-driven process empowers the oil & gas industry to become more durable, robust and competitive.

Discovered on the shallowest formation in Myanmar offshore field at 500 meters subsea, this reservoir is perhaps one of the most challenging reservoirs to develop in many aspects such as; risk of fracking to seabed when performing sand control completion, cap rock integrity and risk of breaching due to completion and production activities, reservoir compaction, and depletion-induced subsidence. Generally, the producing reservoirs currently developed in this field sits between 700 to 2500 meter subsea, mTVDss. Cased Hole Gravel Pack (CHGP) as sand control completion method is selected to develop the reservoir from 700 to 1650 mTVDss. None of the shallow reservoirs (shallower than 700 mTVDss approximately) has been developed in the field before, due to some technical challenges previously mentioned. Owing to these reasons, reservoir engineer and well completion team initiated feasibility study focusing on advanced Geomechanical modeling and alternative way of sand control completion combined with full project risk assessment, ultimately, to unlock huge gas reserves trapped in this field. The reservoir is finally developed with infill well and new completion technique ever been used in the company. To develop this shallow reservoir, infill well drilling with sand control completion is required. The technical analysis on the following problems was comprehensively performed to ensure that the reservoir was feasible, doable and viable to develop. Reservoir compaction and subsidence occurring with stress and pressure changes associated with depletions would not create potential hazard to production facilities. Cap-rock is stable with no breaching over entire life of reservoir depletion. No potential fault is reactivated upon depletion. Sand control completion is able to be performed safely with well-confined fracpack (risk of frac growth to seabed). Upon depletion, integrity of casing and cement is acceptable when reservoir is compacted. Full risk assessment aspects of completion operation are scrutinized. These problems were mainly analyzed using coupled 3D Geomechanical model focusing on this shallow reservoir in the area of this particular wellhead platform. Briefly speaking, the 3D Geomechanical model was coupled with reservoir pressure depletion to find stress and displacement of reservoir rock and casing due to production. The methodology is called one-way coupled modeling. To be more precise, the pre-production stress of the reservoir at initial pressure was determined and used to calculate subsequent stress change from depletion (production). Pressure depletion will increase effective stress and hence create deformation of reservoir rock which may induce underground subsidence and casing integrity. On this study, four stress-steps of pressure depletion were computed i.e. initial pressure, 25% depletion, 50% depletion and 75% depletion. On each step, stress equilibrium was simulated using finite element software. This project makes the pending development of shallow reservoir in this field doable and viable. All risks associated with well completion and production-induced depletion were deliberately reviewed and mitigated. Based on this study, the most critical risk is gas leak through seabed due to sand control completion activity (CHGP). Apart from this, the other risks such as seabed subsidence, cap-rock breaching, fault reactivation, and casing integrity upon compaction were consciously addressed, reviewed and prevented. The major risk on sand control completion was finally mitigated. The conventional extension pack was avoided and replaced with the completion technique, a so-called circulating pack. Circulating Pack is one of CHGP technique where the pumping rate and pumping pressure maintained below fracture extension rate and fracture extension pressure. This pumping rate and pumping pressure will not introduce the fracture in the formation but still able to carry proppants and place them in the annular between screen and casing to provide sand control means. Although the sand control performance of circulating pack is not up to High Rate Water Pack (HRWP) or Extension Pack, together with control of minimum drawdown and production rate will enhance the sand control performance and prolong production life. Ultimately, unlock the potential in this shallow reservoir. The well has finally been successfully completed under tailor-made design and real-time data acquisition. The reservoir has been producing successfully with the rate of about 5 MMSCFD with good flowing wellhead pressure at 590 psi similar to the design. Ultimately, this alternative approach enables the development of this shallow reservoir where the new reserves of 20 BSCF has been added to the project. This project can be a good lesson for future development of other shallow reservoirs worldwide.