Divided-Time Data-Transmission System Uses a Microchip Storage Ball
Authors: Carpenter Chris 
Published: February 2023

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22368, “Study and Implementation of a Large Amount of Data From a Divided-Time Transmission System Using Microchip-Storage-Ball Release While Drilling,” by Sanguo Li, State Key Laboratory of Shale Oil and Gas Enrichment Mechanism and Effective Development and SINOPEC, and Ruixiang Gao and Jibo Li, SINOPEC, et al. The paper has not been peer reviewed. Copyright 2022 International Petroleum Technology Conference. Reproduced by permission.

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A key question posed in the field is how to transmit logging-while-drilling (LWD) data losslessly back to the surface effectively. Conventional LWD tools face challenges in transmitting all data to the surface efficiently. The complete paper proposes a method that uses the concept of a flash drive downloading and exchanging data among computers.

Methodology
Two conventional methods exist for data exchange between computers, one of which is network data transmission. The speed of network data transmission determines the efficiency of data exchange between computers. The other method is to use a flash disk to copy and transfer data between computers.
Similarly, the downhole LWD tool and the surface data computer can be regarded as two computers. When the bandwidth of the real-time network between surface and underground is limited, the principle of a flash drive dumping and exchanging data between the computers can be used. First, LWD data are dumped into a microchip storage ball (MSB). The circuit sends a release command to the power device to release the MSB from the drill collar. The MSB is carried up to the ground by the drilling fluid and will be recovered on the ground. The data in the MSB then will be uploaded to a computer. The releasable time-divisional data-transmission system mainly consists of MSBs for storing LWD data, sealed chambers for storing the MSBs, a power device for releasing the MSBs, and a circuit for detecting the release signal and controlling the release operation.

Large-Capacity MSBs
An MSB essentially is a flash drive for storing LWD data. Because of the space constraints of downhole release tools and the limitations posed by the downhole drilling environment, an MSB must have characteristics such as large capacity, small size, high pressure resistance, high temperature resistance, low power consumption, high performance, and high-speed data-dumping capability. In the presented method, the control and power management module controls the data read/write (R/W) command and the power supply to the MSB so that it can read data from the LWD tools and save it using the RS485 communication mode. The network topology of the RS485 mode can send data to multiple MSBs simultaneously.
The MSB uses an MSP430 chip to manage reading, writing, and erasing of data. The capacity of the memory chip determines the data capacity of the MSB. Currently, the data capacity of one MSB is 1 Mbit. The diameter of the MSB circuit board is 11 mm. The power supply cable and RS485 cable are connected to the circuit board. This type of wired power supply and data transmission eliminates the need for a battery and a wireless data-exchange module.
The MSBs are installed in the sealed chambers of a downhole release tool. Four contacts are designed on an MSB to supply power and to connect the data-circuit system. The four contacts on the MSB are connected to the corresponding four spring contacts in the sealed chambers.