Eric C. Sullivan

Sensing at the bit through a modular measurement device

An accurate determination of weight and torque at the bit is essential to maximize drilling performance and to reduce overall cost. With the increase in complexity of wells for oil and gas production, efficient drilling is becoming extremely important. Due to complex wellbore geometry and dynamics resulting from drilling action and formation properties, energy losses have increased tremendously. Such losses and uncertainty in the amount of energy transferred to the drill bit can impair an operators ability to achieve cost-effectiveness and to optimize performance. The paper describes a memory-based, modular device that can reside inside a drill bit without altering bottomhole assembly (BHA) stiffness and hydraulic requirements. The device can provide accurate measurements closer to the drilling action than other devices on the market. The paper demonstrates the capabilities and the benefits of the tool and shows data obtained through laboratory and field testing. The paper first describes a bit-based modular device, its functionality and its use in capturing acceleration, rotation, weight, and torque at the bit. We also present a case study to show the importance of such parameters in drilling and a validation relative to rig-based data acquisition tools.

Bit Dysfunction Characterization Using a Sensor System at the Bit

Drilling operations represent a major cost in discovering and exploring new petroleum reserves. Poor drilling performance, for example low ROP, can lead to high cost per foot. In order to optimize the performance of drill bits, the dynamic behavior of the bit and the drillstring has to be monitored. In recent developments, we have deployed a sensor / data acquisition (DAQ) system that is mounted at the bit, which can monitor the behavior of the drill bit and dynamic dysfunctions associated with the operating parameters, different rock formations and rock/bit interactions. A modified shank accommodates the sensor / DAQ system. Its location was determined based on extensive analysis of the bit’s structural integrity. Initial tests verified the ability of the system to identify PDC bit dysfunctions, such as backward whirl — one of the most bit damaging events in the drilling operation. Placing a sensor system in the bit allows for accurate pattern recognition and severity determination in terms of dynamic dysfunctions of the bit and can aid in optimizing drilling parameters in pursuit of increased ROP and reduced drilling costs.Copyright