Evaluation of Real-Time and Post-Drilling Petrophysical Data Acquisition Impact on Wellbore Stability and Mechanical Rock Integrity

Abstract

The objective of this paper is to examine filtrate and mud solids invasion effect on wellbore stability and rock mechanical integrity. A stable wellbore depends on the mechanical and chemical interaction between the wellbore fluid and the walls of the wellbore. Excessive wellbore pressure can cause lost circulation and low pressure of the wellbore can cause blowout or collapse. Multiple factors affect mechanical integrity of the rock including the time at which the acquisition of rock mechanical data was taken in the subsurface. The impact of invasion is measured by the exploitation of real-time and post-drilling petrophysical data. A thorough investigation of invasion and its effect on rock mechanical properties is performed to establish a full understanding of the association between time dependency and rock integrity. A mechanical earth model (MEM) is built utilizing petrophysical data acquired in both real-time and post-drilling. Mechanical properties are then cross checked with core measurements to examine the accuracy of the results. The effect of invasion is then highlighted showcasing the time dependency effect on both wellbore stability and rock mechanical integrity. Leveraging real-time and post-drilling petrophysical data across abrasive sandstone formation is key to investigate invasion effects. The effects were witnessed in the readings of resistivity. Separation of deep, medium, and shallow resistivities were observed highlighting the invasion effect due to the time passed after the drilling process and before logging the section. When it comes to invasion effects on strength of the rock, an (MEM) was run on a well with both LWD and wireline acoustic data. Fracture point was analyzed for the effects of invasion. A data comparison is highlighted showcasing the effect of time on the integrity of the rock. Capillary force and osmotic pressure effects are examined and cross checked with the logged data and wellbore stability impact. This paper examines the direct impact of invasion on the mechanical properties of the rock along with wellbore stability. Complex formations can be problematic in lithology during the drilling operation where it might be capable of creating issues such as stuck pipe. The geomechanics of borehole stress has a direct impact on the hazards and problems encountered during drilling operation which causes inefficiency in terms of time and cost spent operationally. The full understanding of invasion effect is a potential solution to such issues.