INFLUENCE OF SURFACES ON BORING OF WELLS WHILE DRILLING IN ANISOTROPIC ROCKS

Abstract

Relevance. Deviation from the design trajectory of wells leads to failure to fulfill the drilling task. The main geological conditions affecting the curvature of the well include stratification, shale, fluidity, fracturing, porosity, intermittency of rock layers of different hardness, crushing zones, faults, voids, and solid inclusions. A significant part of the rocks drilled are anisotropic. The rock anisotropy index for drillability characterizes the degree of influence of the sum of factors on the natural curvature of wells. These factors primarily include the type of tool and the parameters of the drilling mode. The struggle with natural curvature often causes technical difficulties and is associated with a large investment of time. In this regard, it is relevant to study the features of drilling under conditions of rock anisotropy and to consider the possibilities of influencing the curvature of wells with increased fluidity. The aim of the research is to determine the possible effect on the natural curvature of wells when drilling in anisotropic rocks. Object: anisotropic rock destruction mechanism. Methods: experiment, analytical studies, analysis. Results. The decrease in anisotropy during drilling is actively influenced by flushing fluid with a surfactant on the rock prefracture zone. Such an effect tends to eliminate the unevenness of the face damage when the tool cutters move towards and after the fluidity planes, which is explained by a more intensive decrease in the strength characteristics of anisotropic rock precisely in the direction along the fluidity planes. The use of a flushing agent with the addition of a surfactant makes it possible to reduce the ratio of the rate of milling the rock in the wall of the well and the deepening of the bottom in combination with a high mechanical drilling speed under certain conditions. This circumstance is associated with the possibility of active penetration into the cracks of the prefracture zone of the washing agent with a surfactant.

Keywords

• anisotropy
• curvature of wells
• surfactants
• milling ability
• drilling tool
• fluidity
• fracture mechanism
• prefracture zone