Geology Reference
In-Depth Information
10.3 MWD Sensor Developments in China
Well logging involves multiple sensors, among them acoustic, resistivity,
NMR, formation testing (for permeability and pore pressure), annular pressure,
direction and inclination, and so on. A significant amount of information is
available from oil service company websites, e.g., those of Schlumberger,
Halliburton, BakerHughes and others. In this section, we describe recent CNPC
engineering and research activities in logging and “geosteering” (that is,
directional drilling guided using integrated real-time geological information) -
data generating functions that drive the demand for high-data-rate telemetry.
These efforts mirror those of the West, and are becoming commercially
important in many parts of the world - and especially so, given Chinese
advantages in labor and manufacturing costs. Little information is available in
the West about Chinese activities and here we provide insight into the
company's MWD activities. Photographs of tools, laboratory and field work are
presented, courtesy of CNPC, but detailed hardware and software specifications
are omitted because they are rapidly evolving, given the continual drive toward
deeper HPHT offshore wells. The greater part of this topic focused on theory
and laboratory telemetry work and it is worthwhile in this closing chapter to
consider related sensor development and field testing.
10.3.1
DRGDS Near-bit Geosteering Drilling System.
10.3.1.1
Overview.
CNPC's Near-bit Geosteering Drilling System or “DRGDS” is jointly
developed by CNPC Drilling Research Institute, Beijing Petroleum Machinery
Factory and CNPC Well Logging Company Limited. This system integrates
advanced drilling, well logging and reservoir engineering technologies and
utilizes near-bit geologic and engineering parameter measurement with drilling
control to optimize wellbore placement within petroleum-bearing layers. Based
on information acquired while drilling, DRGDS adjusts and controls in real-time
the trajectory of the well so that the drill bit follows payzones as closely as
possible. In other words, it recognizes hydrocarbon zones while drilling and
provides complementary geosteering functions.
10.3.1.2 DRGDS tool architecture.
DRGDS is composed of several elements, namely, Near-bit Measurement
and Transmission Steering Motor (CAIMS), Wireless Receiving System
(WLRS), Positive Pulser MWD (DRMWD) and Ground Information Processing
and Steering Decision-making Software System (CFDS), as shown in Figure
10.3.1-1. CAIMS architecture is given in Figure 10.3.1-2 and it is composed of
Motor Assembly (bypass valve, screw motor and shaft assembly), Near-Bit
Measurements and Transmission Sub (NBMTS), Ground Adjustable Bent
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