Experimental Study of Drilling Fluid's Filtration and Mud Cake Evolution in Sandstone Formations

Abstract

In real time drilling, the complexity of drilling fluid filtration is majorly attributed to changing mud rheology, formation permeability, mud particle size distribution (PSD), filter cake plastering effects, and geochemical reaction of particles at geothermal conditions. This paper focuses on quantifying the major effects as well as revealing their contribution toward effective wellbore stabilization in sandstone formations. We conducted an extensive experimental and analytical study on this subject at different levels. First, we used field application and the results as guides for our experiments. We have considered both oil-based mud and water-based mud. Next, we optimized the mud particle size distribution (PSD) by carefully varying the type, size, and concentration of wellbore strengthening material (WSM). Laboratory high pressure high temperature fluid loss tests were carried out on Michigan and Bandera Brown sandstones. The results from these tests identify the formation heterogeneity and permeability in successful wellbore stabilization. Filter cake permeability calculations, using the analytical model for linear systems, were consistent with filtration rates, and the expected trend of permeability declines with time. Finally, we investigated the evolution of internal filter cake and plastering mechanism, using scanning electron microscopic (SEM) analysis. The test results revealed a significant difference in the formation permeability impairment for the optimal mud PSD and WSM blend.

Detection of intervals / layers in sections of the wells with anomalous areas of drilling mud filtrate contamination according to the well logging (with negative test results of horizons)

“…1. Negative test results of formations (with the recommended oil and gas potential according to the welllogging data) in the perforation intervals are caused by the presence of anomalous zones of penetration of the flushing fluid filtrate [24,31]. Among other factors of different nature, the depth of the invasion (penetration) zone (Dzp) is largely controlled by the presence and size of the mud cake.…”

“…However, even the inhibition of filtration into the formation by increasing the mud cake does not always contribute to the formation of small penetration zones. There are many examples of this, when under all the positive conditions regarding the reservoir characteristics of the formations, the presence of mud cake, the tests did not receive significant inflows of fluids into the wells [17,[24][25][26]. In addition, the technological parameters of drilling significantly influence the test result.…”

Application of Anhydrous Calcium Sulfate as a Weighting Agent in Oil-Based Drilling Fluids

“… 13 − 15 The composition of the filter cake depends on several factors, such as solid additives in the drilling fluid, the differential pressure between mud and formation, and the geology of formation. 14 The filter cake removal process involves the chemical dissolution of weighting materials.…”

Bitumen Recovery from Crude Bitumen Samples from Halfaya Oilfield by Single and Composite Solvents—Process, Parameters, and Mechanism

“…Since 2007, heterogeneous and active bituminous formations have been encountered in the development of Yadavaran oilfield in Iran, Halfaya oilfield in Iraq, the deep-water oilfield in the Gulf of Mexico, the tar sands in Canada, etc. [1,2,3,4,5,6]. Bituminous formations have plastic and creep properties, and the bitumen adhesion property is always strong (Figure 1).…”