Abstract
Yuanba Gas Field is one of the most difficult fields categorized as Super-deep and high-pressure high-temperature (HPHT) reservoirs to develop not only in China but also in the world. It's buried in vertical depth (TVD) of nearlly 7000 m, and with pressure as high as 70 MPa while temperature from 149.5°C to 157.4°C, meanwhile, the average concentration of hydrogen sulfide (H2S) and carbon dioxide (CO2) are 5.14% and 7.5%. In order to successfully exploit this gas field, many problems must be solved in well testing tecniques.
In this paper, we review the most common failures of HPHT sour gas well testing tools and tubular and generalized three major failure types based on analysis of more than 80 wells*times, meanwhile, the potential reasons related to each kind of failures are analyzed. Improvements on tools and operation techniques are conducted. The mandrel of the testing packer is optimized on the basis of axial force simulation and tensile strength is increased from 383 to 618 kN. Three kinds of well testing string assembly are formed to accommodate different well types, different combination operations (i.e., combination of perforation and well testing, combination of perforation-acid stimulating-testing). Well killing and pluging techniques are improve to guarantee the succesful ratio of well testing operations.
The research reviewd field experience and proposes development techniques for well testing of HPHT sour gas field. It can also be taken as a reference for economic and safety development of other reservoirs in extremely harsh environment.
