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Abstract Failures of resin-coated proppants have been primarily attributed to incompatibility between fluid chemistry and the resin, insufficient closure stress, the practice of flowing the well back too aggressively, or stress cycling. This paper describes the failure mechanism that may be more predominant than any of the others: curing too fast. Proppant consolidation kinetics were studied with the use of differential scanning calorimetry and compressive-strength development. Additional studies to determine ultimate compressive-strength development and the effects of flow erosion and stress cycling on resin-coated proppants were performed. This study has determined that the temperature profile and time before proppant grains are compacted and closure stress during curing are critical factors affecting consolidation properties. The investigation also resulted in the identification of the appropriate resin-coated proppants and guidelines for their uses in proppant flowback control in hard-rock fracturing and in sand control of soft formations as in screenless fracpack completions. P. 587
Abstract A near-uniform well (production) inflow or (injection) outflow profile delays early water breakthrough and further decreases water cut which results in higher oil recovery. Field experience has shown that wells producing from, or injecting into, multiple layers and/or reservoirs benefit from an Inflow Control Device (ICD) completion's ability to reduce the in/out-flow imbalance along its length. The standard ICD completion design workflow involves selection of the โstrengthโ of the ICD's restriction based on the incomplete knowledge of the reservoir that is available prior to drilling the well with several commercial softwares available for this. However, more complete reservoir data becomes available once the drilled completion zone has been logged and the data analysed. There follows a short period of time during which the engineer must judge whether the planned ICD completion design is โfit-for-purposeโ or needs further consideration. The availability of a rapid ICD completion design methodology that does not require access to computationally demanding commercial software would be highly beneficial at this time. This paper presents a workflow which meets the above requirements. It extends our previous analytical approach to ICD sizing to directly relate the uniform-strength ICD completion design to the predicted heterogeneity of the open-hole inflow profile together with the consequent loss in well productivity from the ICD's flow restriction. The workflow combines a series of dimensionless, universal type curves and analytical solutions in a relatively simple and fast process to find the desired ICD design. A new completion design can be made immediately after drilling has been completed to provide the desired level of inflow variation from the latest predicted level of reservoir and fluid inflow heterogeneity determined by a โquick-lookโ evaluation of the well's log data. The same design procedure can be used to select ICD completion designs that are a compromise between two competing objectives: increasing the uniformity of the inflow profile and minimising the reduction of the well's productivity index that results from the extra pressure losses imposed by the ICDs. Two typical examples of the workflow's application are provided. The first one examines whether it is necessary to change the ICD completion design when drilling problems result in a reduction of the well's completion length. The second example evaluates the impact of the actual reservoir permeability profile being more heterogeneous than originally expected. The workflow's design philosophy was confirmed by commercial numerical simulators recommending the same ICD completion design in both cases. This work extends our earlier analytical approach to ICD sizing. This new ICD completion design workflow can be used by completion design engineers to rapidly analyse uniform-strength ICD completion design options and their consequences on well inflow performance without expensive computational resources. The underlying principles, assumptions and application area of the analytical model are fully discussed in the paper.
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 054 > Block 31/6 > Troll Field > Sognefjord Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 054 > Block 31/6 > Troll Field > Heather Formation (0.99)
- Europe > Norway > North Sea > Northern North Sea > North Viking Graben > PL 054 > Block 31/6 > Troll Field > Fensfjord Formation (0.99)
- (9 more...)
Abstract A new high strength coiled tubing grade has been developed to address the demands for improved axial strength, better fatigue performance and the ability to function at higher operating pressures. Coiled tubing service companies and operators defined several areas where existing coiled tubing grades are not considered capable of performing, including carrying heavier payloads to the well perforation zone and working in today's increasingly longer horizontal sections. Designing a coiled tubing product that meets these requirements presented unique challenges. The project goal was to develop reliable high strength coiled tubing that provides 130,000 psi minimum yield strength and predictable fatigue life. Coiled tubing strength comes from a balance of strength from the initial hot rolled strip and modifications while forming into tubing. However, some coiled tubing manufacturing operations, including welding, can influence those strength characteristics. The process controls during manufacturing, including bias welds and any tube to tube welds needed to assemble long strings; all determine the final properties of the tubing. The high strength tubing has been successfully made using existing manufacturing methods. The initial testing indicates the tubing has high strength with good ductility. Fatigue testing shows superior fatigue performance to existing grades of tubing in both cycles to failure and diametrical growth. This paper will cover the development program inclusive of strip manufacturing, tube forming, welding and other processes including the quality control necessary for assuring consistent properties. Initial application trails to verify operating characteristics will also be reviewed in the paper.
ABSTRACT Grout placement techniques, technology of grouting materials, and methods for monitoring grout quality and grout placement are presented. Placement methods using new generation high pressure packers and inflation-grout manifolds are discussed. High pressure packers have made single stage grouting jobs a practical reality. Reliable inflation-grout manifolds have eliminated many lines previously needed for packer inflation and placement of grouting materials. In addition to traditional grouting materials, new materials to promote high bond strength, control self-desiccation, and minimize shrinkage are discussed. Grouts are classified according to use and typical examples are given. Methods and equipment for controlling grout density and grout placement are included. INTRODUCTION Platform grouting is the process of placing a cementitious material into the annulus between a jacket leg and pile. This operation has advanced to the point now that an operator has a variety of methods, materials, and tools from which to choose. For example, at least five different methods for grouting platform legs are commonly used with variations existing within each method. Terms for each of these methods, although not standard, might be (1) conventional two stage, (2) packer, (3) balanced pressure, (4) two stage delayed set for insert piles, and (5) two stage inner string for insert piles. Recent advances in methods, materials, and tools have helped make platform grouting more trouble-free and dependable. This paper will review these advances and provide an overview of current platform grouting in general. GROUTING METHODS Conventional Two Stage As shown in Fig. 1, this method usually involves a mud wiper seal at the bottom of the annulus. This serves to help reduce mud contamination of the annulus as the pile is driven through the jacket leg and it also helps support the first stage of the grout. This technique normally involves running two separate grout lines from the surface. The first stage line enters the annulus just above the mud wiper seal. Second stage line enters the annulus 5 to 30 ft above the first stage grout line depending on the length of plug required. First stage grout is normally a quickset type and fills up to the second stage grout line entry level. While the first stage is setting, water should be circulated through the second stage grout line to displace any grout that may have covered the second stage port. Once the first stage grout is set, the second stage is injected to the desired height in the annulus. An improvement to this procedure, shown in Fig. 2, makes it possible to accomplish the grouting through only one grout line from the surface. One line is run from the surface to the lower grout inlet. A pipe is run from the upper grout inlet to a sleeve-type flow control valve installed in the grout line at the same elevation as the upper grout port.
ABSTRACT: Tensile strengths from the direct tension test and the Brazilian test are compared for the purpose of material property calibration for DEM modeling. We show that size effect in direct tension is statistically insignificant. Sample size is not critically important in calibrating the tensile strength. On the other hand, failure mechanisms in the Brazilian test depend on not only the material properties but also sample size. In addition to the conventional diametrical splitting failure resulted from initiation and propagation of a center crack, alternative failure scenarios involving formation of damaged zones near the loading points are also possible. The Brazilian tensile strength could either underestimate or overestimate the intrinsic tensile strength. Direct tension instead of the Brazilian test should therefore be conducted for material property calibration. We also show that a displacement-softening contact law can resolve the issue of low compressive over tensile strength ratio in DEM modeling. By adjusting the softening coefficient, a realistic strength ratio can be obtained and the conventional diametrical failure pattern can be reproduced in the Brazilian test.