fax 01-972-952-9435. AbstractShallow gas and water flows are a major concern when cementing deepwater wells in many Gulf of Mexico fields, often requiring expensive remedial work, premature well abandonment and respudding. Entire templates can be compromised if a single cement job on surface pipe fails to provide zonal isolation from the shoe up to the mud line.

This paper describes the development and testing of an innovative downhole zonal pressure maintenance device (PMD) developed for open and cased hole well completions. This PMD will be deployed as an integral tubular component in a generation IV single-trip multizone sand control system (STMZ) currently run in deep water and in other unconsolidated soft-rock applications. It will significantly increase the system's capability and provide proven time-saving benefits of such technology into the soft-rock formation arena. Typical generation IV systems currently used isolate the discrete zones from one another and the wellbore. The operational steps include setting the top-most packer first. This process isolates the zones from the hydrostatic overbalance pressure, creating an opportunity for uncontrolled crossflow among zones with differing bottomhole pressures. This crossflow can, and will, move hydrocarbons as well as formation sand into the wellbore therefore certain limitations are placed on the existing STMZ system. The PMD maintains the initial hydrostatic pressures on each zone independently to help prevent uncontrolled crossflow and its detrimental effects. The PMD construction is totally mechanical and fully autonomous, not requiring any signals from the surface for its operation. It has built-in intelligence to sense the array of initial hydrostatic pressures in various zones and to store them for subsequent use. Prototype tools were developed and tested in the laboratory, simulating near realistic multizone completion operations. The PMD design enables the amount of fluid leakoff into the formation to be minimized, thereby reducing formation damage. This capability is accomplished by automatically adjusting the PMDs to the respective zones to reflect the individual differences in reservoir pressure; it is particularly useful for completing wells wherein significant differential pressure exists between compartments because of the depletion that has occurred in some reservoirs. The paper illustrates expected results on a multizone completion and displays the pressure maintenance behavior resulting from the use of this device. Tests were conducted in the laboratory to validate the tool performance under extreme conditions of high leakoff rate in conjunction with an abrasive fluid with plugging tendency (oil-based mud). Another condition simulated relatively high pressure differential (2,000 psi) while reversing out after a "frac pack" operation. The tool design incorporates state-of-the-art technologies, such as 3D printing and hydraulic miniaturization using implementation techniques unique to oilfield applications. Generation IV single-trip multizone system technology has been a key enabler for formations, such as those found in the Lower Tertiary of the Gulf of Mexico. The PMD provides a novel tool to extend these multizone applications to unconsolidated formations and to multizone reservoirs with high reservoir pressure differentials.

In re-entry or workover type situations, the primary performance objectives determined during the initial well completion remain the same, especially in deepwater, high-rate wells. These generally require running the largest-diameter casing string possible, since the dimensions of the completion equipment can determine critical well objectives. Especially in reservoirs requiring sand-control reliability, production rate becomes a primary concern in the workover situation. Issues regarding critical erosional velocities, reservoir sweep or recovery efficiency and feasibility of installing flow controls or intelligent-well equipment remain. For mature wells requiring a side-track, the current well-construction practices necessitate reduced dimensions of the sand-control completion-equipment. This paper presents a well construction/completion methodology that supports increased completion-component dimensions in side-tracked or new wells, potentially improving overall well performance. The system is suitable for any openhole gravel-pack completion. Introduction Because of the prevailing high prices of hydrocarbons and the difficulty in finding new reserves, the oil and gas industry has made efforts to increase the rates of recovery in mature fields. The average rate of recovery is 35% for oil and 70% for gas; however, the current direction is to try to increase the recovery rate of oil to 50% and more than 80% for gas.1 Mature fields — also called brown fields1 — are those oil and/or gas fields that are approaching the end of their productive life. Typically, these mature fields have been producing for more than 30 years and are located in certain geographical areas for different historical and geopolitical reasons. Brownfields are commonly located in the North Sea, United States (onshore), South America, Russia and Australia. These fields produce over 70% of the world's oil and gas production. Brownfields possess the advantage of an existing infrastructure, providing the least expensive means to increase reserves and production. In both enhanced reserves recovery projects for mature fields using sidetracks from existing wellbores and for new well field development projects, wellbore size and casing design requirements are key determinants for well construction costs. Yet, wellbore size and tubulars designs must be balanced against cost factors in order to accommodate certain critical requirements, including:rig- and drilling-equipment limitationssub-sea preventer stack dimensionsexisting wellbore geometry and trajectory limitations for sidetrackstubular sizing needed for reservoir productivityhole size needed to accommodate gravel-pack completionscasing size needed for downhole flow-control equipmentcasing size needed for artificial-lift equipment. Oil fields developed for openhole deviated or openhole lateral gravel packs typically install and cement production casing or liners. The openhole production interval is then drilled using the next smaller bit size. The single-trip method described in this paper is more cost efficient in that it does not require changing hole sizes and eliminates at least one pipe round trip. In this new method, the production liner and hanger are combined with the openhole gravel pack assembly and run into the well in a single trip. The gravel-pack service tool and accessory equipment is configured to allow gravel packing and liner cementing in consecutive operations within the same pipe trip. In this paper, a system, which targets an economical increase in production and reserves in mature unconsolidated reservoirs/fields, is described. The methodology accomplishes these achievements through using:Larger screen ODs, which improve flow area and screen life, thereby increasing productionMinimized pipe trips, which impact completion costs by saving rig time and wearA one-shot deployment of liner and screen with an option of gravel packing and liner cementation.

fax 01-972-952-9435. AbstractShallow gas and water flows are a major concern when cementing deepwater wells in many Gulf of Mexico fields, often requiring expensive remedial work, premature well abandonment and respudding. Entire templates can be compromised if a single cement job on surface pipe fails to provide zonal isolation from the shoe up to the mud line.

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