Sand Production In Wells Research Articles

Sand control screen selection for cased dual‐annulus gas offshore wells based on scaled laboratory tests

AbstractThis paper assessed and ranked several alternatives to control sand production in a well recompletion effort of offshore gas wells that have experienced massive sanding. The aim was to select an appropriate thru‐liner sand control system to increase well productivity. Four different screen types were evaluated, including a wire‐wrapped screen (WWS), slotted liner (SL), punched screen (PS), and a new multi‐layer open cell matrix polymer (OCMP) filter resembling gravel‐pack. The performance of screens regarding sand production and plugging was evaluated using a sand retention testing facility featuring a custom‐made device that mimics the unique well completion configuration. Further, a novel testing setup was constructed to assess the erosion potential of screens subject to high‐velocity gas and sand flow. All assessments were conducted under the representative actual well conditions. Laboratory tests indicate the superior performance of the OCMP filter compared to the other three options. Even though SL, WWS, and PS performed similarly in sanding, the WWS posed a higher erosion risk, with PS following in second place. The plugging tendency of the WWS was the least among all the options, whereas the PS had the highest tendency. Despite this, the WWS's sanding performance is expected to decline due to its vulnerability to erosion. Overall, the testing results indicated that the OCMP filter provides a promising solution to the issue of sand production in the gas wells being evaluated. However, the interaction of the OCMP filter with potential treatment chemicals in the wells should be tested before it can be used.

Analysis of Test Results of Titanium Filters for Sand Process Control when Operating Wells

The article analyzes the results of testing titanium filters to control sand production processes during well operation. It is shown that due to the decrease in the effectiveness of measures to strengthen the bottomhole zone with resins in the conditions of flooded wells, it was decided to carry out experimental work to combat sand production using downhole filters. The results of pilot tests have shown the fundamental possibility of using of anti-sand downhole filters with titanium filter elements (PSTFE) filters as an effective means of controlling sand production in wells, where the reservoir is represented by loose sand without clay material.

ASSESSMENT OF BASIC GEOLOGICAL BEDDING CONDITIONS OF OPERATIONAL FACILITIES IN PRODUCTION FORMATION FLUIDS

The total overburden pressure on the seam wing is greater than the lateral pressure, and on the fold dome, on the contrary, the lateral overburden pressure is greater than the total. As a result, the layer material flows from the wing zones to the domed part, as a result of which the layer thickness on the dome increases, which is noted in the studies of Soviet scientists. Investigating the mechanism of formation fracture during water injection, we found that high fracture pressures are observed in wells located in the lower parts of the structure (fold wings), and smaller ones in the higher parts (fold dome). When the stability of rocks in the near-wellbore part of the formation is disturbed during the operation of wells, studies have established that fresh water causes hydration and swelling or dispersion of clays, which act as a cementing material in the rocks. This can lead to both a decrease in permeability and the development of destruction processes in the near-wellbore part of the formation. Prevention of this effect during well development is achieved by using saline formation water or fresh water with additives of hydration inhibitors, such as NaCl (5-10 %), CaC12 (1-3 %), KC1 (1-3 %). Another type of well completion complications is clogging of the near-wellbore part of the formation. According to available data, mud-acid treatment restores the rock permeability by about 50 % of the original value, while conventional flushing does not exceed 30 %. Therefore, the fight against sand production in wells should begin even during their construction by the correct selection of working fluids. The stability of sand vaults was investigated with various forms of sand grains and saturation of sand with fluids during fluid filtration. Laboratory studies have established that the stability of the vaults depends on the degree of roundness of the sand and the saturation of the liquid. The presence of clay particles in the sand increases the stability of the vaults, and an increase in water saturation decreases it. This is confirmed by the results of the analysis of the effectiveness of the introduction of thermal methods for enhancing oil recovery of clay sandstones saturated with high-viscosity oil. Besides, another of the main rheological properties of the rock is creep. Significant creep is inherent in associated rocks (clays, mudstones, shales). Krivoy Rog rocks, for example, quartz-sericite shale and arkosic sandstone, have creep, averaging 20-35 % of the initial elasticity of deformation, with the greatest deformations occurring in the first 1.5-2 days of loading. It was found that to ensure the stability of the fixed part of the formation in the annulus of the bottomhole zone of the well, static equilibrium should be maintained in the porous medium. Rocks with low values of rheological properties (with a low relaxation rate) provide a longer resistance of the near-wellbore part of the formation to destruction during well operation.

Исследование режимов эксплуатации газовых скважин в осложненных условиях

The influence of reservoir rock properties on sand production in wells is considered. It was concluded that the rock should be considered rather not from the point of view of its strength, but from the point of view of the type of cementitious substance and its distribution. When predicting sand production, it is necessary to take into account the internal stresses of the rocks, as well as the change in these stresses during drilling, perforation and operation of the formation due to the violation of their initial state. Within the framework of this work, an analysis of the main causes of sand production during the operation of gas wells and the negative consequences of sand production for gas production equipment is presented. It has been established that water breakthrough, formation depletion, pressure drop at the bottom of the wells due to their frequent shutdown are the main prerequisites for the removal of sand from the bottomhole formation zone. Sand production is associated with such negative consequences as plugging in wells, erosion of underground and surface equipment, collapse of the top of the bottomhole formation zone and production strings. The main technologies for the prevention and elimination of accidents associated with the removal of mechanical particles from the reservoir are considered. Based on the research results, an algorithm was proposed for selecting technological modes of well operation in conditions of water and sand. The parameters for choosing the optimal operating mode of a gas well are substantiated, in which sand is not extracted with the subsequent disabling of downhole and wellhead equipment, the integrity of the bottomhole zone is not violated, and the well is not selfcontained. The results obtained can be applied to improve the efficiency of gas wells operation and predict their trouble-free operation.