Experimental and Theoretical Investigation of Clogging Processes near Production Wells using X-ray Tomography

Zitha

SPE European Formation Damage Conference &Amp; Exhibition

et al. 2013

Injectivity decline is an issue during produced-water reinjection (PWRI) for water disposal in aquifers, waterflooding, chemical enhanced oil recovery, and geothermal-energy exploitation. A novel model for injectivity decline under flow conditions reminiscent of PWRI was developed taking into account deep-bed filtration and buildup of external filter cake. A distinct feature of the model is that it describes particle-retention kinetics responsible for internal filtration by an exponential decaying function of the retained-particle concentration. The corresponding nonlinear governing partial-differential equations were solved numerically and coupled with a known analytical model for external filtration with the concept of transition time. Coreflood experiments consisting of the injection of brine containing suspended hematite particles (volume fractions in the range of 2 to 6 ppm) were also performed. Computed-tomography (CT) scans of the core were taken to obtain deposition profiles along the core at different times. In addition, effect of various parameters (particle concentration and number of grids) on injectivity was investigated. From CT-scan and optical-microscope analyses, it was found that surface deposition in the porous medium and face plugging at the injection face of the core were responsible for decline in injectivity. The transition time from pure internal to external filtration was accurately determined from the CT-scan and pressure data. The newly proposed model and experiments were found to be in excellent agreement, indicating that the adopted retention function is a good heuristic description of particle retention.

Section: Resultsmentioning

confidence: 99%

A Novel Water Injectivity Model and Experimental Validation using CT Scanned Core-floods

Zitha

SPE European Formation Damage Conference &Amp; Exhibition

et al. 2013

“…The other (non‐reference) wells were located in coarser grained and more permeable formations and had a higher flow velocity (Table 1 ). Grain size and permeability are factors that have been shown to have a large influence on borehole clogging rates (e.g., de Zwart 2007 ).…”

Section: Methodsmentioning

confidence: 99%

Field Testing of a Novel Drilling Technique to Expand Well Diameters at Depth in Unconsolidated Formations

Schans

Bloemendal

Robat³

et al. 2022

Groundwater

Larger well diameters allow higher groundwater abstraction rates. But particularly for the construction of wells at greater depth, it may be more cost-efficient to only expand the borehole in the target aquifer. However, current drilling techniques for unconsolidated formations are limited by their expansion factors (<2) and diameters (<1000 mm). Therefore, we developed a new technique aiming to expand borehole diameters at depth in a controlled manner using a low-pressure water jet perpendicular to the drilling direction and extendable by means of a pivoting arm. During a first field test, the borehole diameter was expanded 2.6-fold from 600 to 1570 mm at a depth of 53.5 to 68 m and equipped with a well screen to create an expanded diameter gravel well (EDGW). In keeping with the larger diameter, the volume flux per m screen length was two times higher than conventional 860 mm diameter wells at the site in the subsequent 3 year production period. Although borehole clogging was slower on a volumetric basis and similar when normalized to borehole wall area, rehabilitation of particle clogging at the borehole wall was more challenging due to the thickness of the gravel pack. While jetting the entire borehole wall before backfilling holds promise to remove filter cake and thus limit particle clogging, we found that a second borehole (expanded 4.1-fold to 2460 mm) collapsed during jetting. Overall, the EDGW technique has potential to make the use of deeper unconsolidated aquifers economically (more) feasible, although further understanding of the borehole stability and rehabilitation is required to assess its wider applicability.

“…For ATES systems, the wells are alternately injection or pumping wells according to the season. As such, if the capacity of the wells would decrease over time due to clogging, this would be detrimental to the overall efficiency and capacity of the ATES system (Jenne et al, 1992;De Zwart, 2007).…”

Section: Membrane Filtering Indexmentioning

confidence: 99%

Assessing the potential of low transmissivity aquifers for ATES systems: a case study in Flanders (Belgium)

Tas¹,

Simpson²,

Hermans³

2023

Preprint

The Member States of the European Union pledged to reduce greenhouse gas emissions by 80-95% by 2050. Shallow geothermal systems might substantially contribute by providing heating and cooling in a sustainable way through seasonally storing heat and cold in the shallow ground (<200m). When the minimum yield to install a cost-effective aquifer thermal energy storage (ATES) system cannot be met, borehole thermal energy storage (BTES), relying mostly on the thermal conductivity of the ground, is proposed. However, for large-scale applications, this requires the installation of hundreds of boreholes which entails a large cost and high disturbance of the underground. In such cases, ATES systems can nevertheless become interesting. In this contribution, we present a case study performed on a Ghent University campus, where the feasibility of ATES in an area with a low transmissivity was determined. The maximum yield of the aquifer was estimated at 5 m³/h through pumping tests. Although this low yield was attributed to the fine grain size of the aquifer, membrane filtering index tests and long-term injection tests revealed that the clogging risk was limited. A groundwater model was used to optimize the well placement while limiting the risk of interactions between the wells resulting in a thermal breakthrough or flooding at the surface. It was shown that a well arrangement in a checkerboard pattern was most effective to reach these objectives. Hence, for large-scale projects, a minimal CO2 output might be reached using a (more cost-effective) ATES system even in low permeable sediments.