Characterization a Self-destructing Filter cake by Using Computer Tomography
- Salaheldin Elkatatny (Texas A&M University) | Ameneh Rostami (Texas A&M University) | Hisham A. Nasr-El-Din (Texas A&M University)
- Document ID
- Society of Petroleum Engineers
- SPE/IADC Middle East Drilling Technology Conference and Exhibition, 24-26 October, Muscat, Oman
- Publication Date
- Document Type
- Conference Paper
- 2011. SPE/IADC Middle East Drilling Technology Conference and Exhibition
- 5.5.2 Core Analysis, 1.8 Formation Damage, 4.1.5 Processing Equipment, 1.6.9 Coring, Fishing, 1.2.3 Rock properties, 2.7.1 Completion Fluids, 3 Production and Well Operations, 2 Well Completion, 1.11 Drilling Fluids and Materials, 4.1.2 Separation and Treating, 1.6 Drilling Operations
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Drilling long horizontal and multilateral wells with very low drawdown makes efficient cleaning and stimulation treatments very challenging. None of the conventional chemical cleaning methods can overcome problems for filter-cake removal in long horizontal and maximum reservoir contact wells because of limitations such as the complex geometry of wells, nonuniform chemical distribution, low contact between cleaning fluids/filter cake, and high chemical reaction rate, especially at high temperatures.
All of these challenges lead us to develop a new system of filter cake removal method that addresses several key problems inherent in the removal of drilling fluid filter cake, cleaning, and stimulation treatments of horizontal and multilateral wells. This system is a water-based drilling fluid that is weighted with calcium carbonate and has a mixture of solid-acid precursor and particulate solid-acid reactive material. This fluid has both functions of drilling and completion and can reach total depth of MRC wells. It has the ability to effectively stimulate the whole horizontal sections after drilling.
Previous work by the authors on this self-destructing drilling fluid system resulted in obtaining the best formula based on the original water-based mud (SPE 136400). High temperature high pressure filter press results (SPE 139087) showed high filter cake efficiency in cleaning the filter cake. Unlike the conventional reactive acids such as HCl, the slow reaction kinetics ensured good distribution of the generated acid across the filter cake.
The objective of this study is to determine the homogeneity of the self-destructive filter cake. Image J software and Grabit software combined with CT scan results were used to determine the filter cake properties such as porosity, permeability and thickness of the self-destructing filter cake system.
Exposure of the fluid to reservoir rock is unavoidable during drilling and workover. In many in-situ hydrocarbon reservoir exploitation processes, cake filtration inherently occurs in these reservoirs. Overbalance drilling of wells into petroleum reservoirs is examples of the processes that cause a cross-flow filtration, which leads to a filter cake buildup over the face of the porous rock and filtrate invasion into the reservoir.
Mud fines and filtrates invade the near-well bore formation and damage this zone.
Filter cake must be removed by different chemical and mechanical means. Removing the filter cake can be accomplished by mechanical means (scraping, jetting) or by subsequent addition of a fluid such as an acid or an enzyme to dissolve at least a portion of the filter cake (Willberg and Dismuke 2009).
All technologies currently used have some drawbacks. Oxidizers and acids have been used for many years to remove filter cake produced by polymer-based drilling fluids. Although these materials could be reasonably effective in attacking individual components of the cake, they are not necessarily efficient when confronted with the tight composite cake laid down on the formation (Almond 1982; O`Driscoll et al. 1988). Therefore, in many cases unreacted polymers stay in place and degrade partially (Stanley et al. 1999).
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