Analysis of Wellbore Skin Samples—Typology, Composition, and Hydraulic Properties

Abstract

The presence of a wellbore skin layer, formed during the drilling process, is a major impediment for the energy-efficient use of water wells. Many models exist that predict its potential impacts on well hydraulics, but so far its relevant hydraulic parameters were only estimates or, at best, model results. Here, we present data on the typology, thickness, composition, and hydraulic properties obtained from the sampling of excavated dewatering wells in lignite surface mines and from inclined core drilling into the annulus of an abandoned water well. Despite the limited number of samples, several types of skin were identified. Both surface cake filtration and particle straining in the aquifer occur. The presence of microcracks may be a determining feature for the hydraulic conductivity of skin layers. In the case of the well-developed water supply well, no skin layer was detected. The observed types and properties of wellbore skin samples can be used to test the many mathematical skin models.

Dipole Flow Tracer Test Models for Identifying Skin Properties and Ambient Groundwater Flow Effects

“…It is well established that the skin is difficult to identify in the field. A specific analysis of the wellbore skin sample in the study of Houben et al (2016), which employed a vertical core drilling into the annulus and the adjacent aquifer of a well, is considered reliable but extremely expensive. Considering that the skin effects on solute transport can be incisively and vividly revealed by the patterns of the BTC through DFTT, it is meaningful to explore the potentials of DFTT in terms of identifying the primary properties of the skin based on theoretical models.…”

Contribution to head loss by partial penetration and well completion: implications for dewatering and artificial recharge wells

“…If the well is properly designed and developed, the second-most significant portion of the total additional well loss occurs in this well skin (e.g. Houben 2015b; Houben et al 2016). Prolonged, costly well development procedures are required to minimize the additional head loss due to well skin.…”

“…Five types of different filter pack material were selected for this study, ranging from medium to very coarse sand, in order to investigate the nonlinear flow head losses in wells (Table 2). Filter pack porosities of 0.34-0.36 are realistic values for the packing density of filter packs of dewatering wells (Houben et al 2016).…”

Analytical solution for heat exchange in energy pile ground considering smear effects

“…To date, many studies have investigated the smear effects of installing prefabricated vertical drains or injection/extraction wells on the consolidation process [11][12][13][14][15][16][17][18][19][20][21] and solute transport process. [22][23][24][25] However, there is no analytical or numerical study of the smear effects on heat transfer in the energy pile foundation. Experimental studies show that driven energy piles are more likely to suffer from thermally induced settlement compared with bored energy piles, [26][27][28][29] which might be attributed to the smear effects on the thermal and mechanical behaviour of soil.…”

“…The soil properties in the smear zone could be different from those in the undisturbed zone. To date, many studies have investigated the smear effects of installing prefabricated vertical drains or injection/extraction wells on the consolidation process 11–21 and solute transport process 22–25 . However, there is no analytical or numerical study of the smear effects on heat transfer in the energy pile foundation.…”