Contamination of Deepwater Well Cementations by Synthetic-Based Drilling Fluids

Abstract

Synthetic based mud (SBM) contamination of portland cement slurries negatively affects the integrity of cementations in oil and gas wells, particularly drilled in deepwater environments. Few systematic studies to assess the effects of SBM contamination on portland cements have been reported in the literature, despite the industry understanding that such detrimental contamination occurs. In addition, solutions to reduce or eliminate the effects of SBM contamination of slurries have not been developed. A multi-phase project has been initiated to study the effects of SBM contamination on slurries, particularly those employed in deepwater wells (where long displacements, restricted circulation rates in tight annular clearances etc. can exacerbate the impact of mud contamination), and to assess which chemical interactions are causing the unfavorable behavior. The first phase of the project was to quantify the effects of contamination on typical portland slurries and to explore formulation changes that would make such slurries more tolerant to contamination. The control in the study was Class H portland cement, which has been the long-standing "workhorse" of the oil and gas industry for primary cementations. Two class H cements and other API cement types were investigated in the work. Alternative cements were also contaminated with the SBM for comparison with the Portland slurries. Results from the first phase of our work clarify the detailed contamination behavior of portland cements, showing the susceptibility of portland slurries to such contaminations. Results for alternative cementing formulations indicate distinctly lower sensitivity to SBM contamination. These results then provide a first set of guidelines on how to minimize and possibly avoid SBM cement contamination, which is expected to greatly help guarantee primary cementing success and proper zonal isolation in deepwater wells.

Contamination of cement slurries with diesel-based drilling fluids in a shale gas well

“…The trend of the compressive strength of cements containing OBMs is similar to the results found by Aughenbaugh et al (2014). To further analyze the reason for this reduction in the strength of cement stone, it is necessary to analyze the cement produced and its structure after hydration.…”

“…Although cement contamination by OBMs is widely understood to be a problem, producing rheological variations, shortened thickening times and reduced strength (Morris and Motley., 1973;Al Khayyat et al, 1999;Fakhreldin et al, 2011;Aughenbaugh et al, 2014), little research has been done in recent years to describe the underlying mechanisms and identify comprehensive solutions. Most of the work done on this topic either by researching effectively spacer fluid to prevent contamination or adding appropriate additives in cement slurry and drilling fluid to improve the compatibility between cement slurry and mud (Brothers and deBlanc, 1989;Skalle et al, 1991;Harder et al, 1993a,b;Fleming et al, 1998;Salehi et al, 2009;Budiawan et al, 2014;Shahvali et al, 2014;He et al, 2014;Farahani et al, 2014;Velayati et al, 2015;Teodoriu and Asamba, 2015;Ariyanti et al, 2015).…”

A Review of Recent Research on Contamination of Oil Well Cement with Oil-based Drilling Fluid and the Need of New and Accurate Correlations

“…In study performed by Aughenbaugh et al [25], it is also seen that for the same class of cement (H-1 and H-2) under the same testing conditions and the same OBF contamination, different results were obtained and the reason for this is unclear. Furthermore, the long-term effect on the mechanical properties of contaminated slurries is examined by few research groups.…”

“…The objective of study carried out by Aughenbaugh et al [25] was to quantify the effects of contamination of various cement slurries with synthetic-based mud (SBM) and look for additives to reduce the effect of contamination. This research was/is divided into multiple phases and these were the objectives of the first phase.…”

“…It is evident that the contamination of oil well cement with OBF causes well integrity issues and there is a need to better understand the effect of this contamination. Research studies [25][26][27][28][29][30] have been carried out in recent years to evaluate and quantify the effect of OBF contamination of oil well cement on the long-term integrity of the well. A summary of these recent studies is presented in the following sections, followed by critical analyses and discussions of the same.…”