Abstract
Fine, small-size, drilled cuttings, if not properly separated using mud conditioning equipment at the surface, are circulated with the drilling fluid from the surface to the bottom hole. These drilled cuttings have a significant effect on the drilling fluid properties and filter cake structure. During drilling long lateral sandstone formations, different cuttings with varied properties will be generated due to sandstone formations being heterogeneous and having different mineralogical compositions. Thus, the impact of these cuttings on the drilling fluid and filter cake properties will be different based on their mineralogy. In this paper, the effect of different sandstone formation cuttings, including arenite (quartz rich), calcareous (calcite rich), argillaceous (clay rich), and ferruginous (iron rich) sandstones, on the filter cake and drilling fluid properties was investigated. Cuttings of the mentioned sandstone formations were mixed with the drilling fluid to address the effect of these minerals on the filter cake thickness, porosity, and permeability. In addition, the effect of different sandstone formation cuttings on drilling fluid density and rheology, apparent viscosity (AV), plastic viscosity PV), and yield point (YP) was investigated. High-pressure high-temperature (HPHT) fluid loss test was conducted to form the filter cake. The core sample’s petrophysical properties were determined using X-ray fluorescence (XRF) and X-ray diffraction (XRD) techniques and scanning electron microscopy (SEM). The results of this work indicated that all cutting types increased the rheological properties when added to the drilling fluid at the same loadings but the argillaceous sandstone (clay rich) has a dominant effect compared to the other types because the higher clay content enhanced the rheology. From the filter cake point of view, the ferruginous sandstone improved the filter cake sealing properties and reduced its thickness, while the argillaceous cuttings degraded the filter cake porosity and permeability and allowed the finer cuttings to penetrate deeply in the filter medium.
Highlights
During the drilling process, an impermeable layer called a filter cake is formed on the face of the drilled formation to minimize the filtration and solid invasion [1, 2]
This experimental study was conducted to address the effect of drilled cuttings of quartz arenite, calcareous, argillaceous, and ferruginous sandstone concentration on filter cake and drilling fluid properties
Based on the obtained results, the following conclusions are drawn: (1) As the quartz arenite, calcareous, argillaceous, and ferruginous sandstone formation cutting contents increased in the drilling fluid, the rheological properties (AV, plastic viscosity (PV), yield point (YP), and gel strength) increased
Summary
An impermeable layer called a filter cake is formed on the face of the drilled formation to minimize the filtration and solid invasion [1, 2]. There are several variables that affect filter cake properties, filtration volume, and invasion depth, such as drilling fluid additives, formation properties, and well conditions (temperature, pressure, and drill pipe rotation). The drilling fluid additives highly affect the filtration properties. Intensive research has been carried out to improve the characteristics of drilling fluid additives to minimize their adverse effect on drilled formations. Silica and ferric oxide nanoparticles were introduced to stabilize the performance of drilling fluid and improve the filter cake properties [3,4,5,6]. The formation permeability and lithology play a great role on the cumulative mud filtrate
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