Features of the underground storages construction in depleted oil and gas condensate fields

Abstract

The paper considers the features of the underground storages (US) construction in depleted oil and gas condensate fields (DOGCFs). The requirements for the structure of the formation, corresponding to the parameters of the object for possible US creation are presented.
 The influence of geological, hydrogeological, mining and technical rock formation conditions on the reliability and tightness of underground storages, including underground gas storages, has been evaluated. The necessary conditions for the US design are analyzed at the example of the Ach-Su oil and gas condensate field, in the presence of a well-explored trap with acceptable parameters for the construction of an underground storage. An important aspect is the geological conditions that meet the criteria for selecting the object: the required structure, the absence of fracturing faults, high reservoir properties of the formation, a sufficient volume of the deposit for the storage. Geological conditions lay the basis for determining the individual characteristics of the US construction technology at each DOGCF. The refined results for the current gas-saturated pore volume and the rate of pressure drop in the formation are presented, which makes it possible to select improved technological indicators in the course of operation of the created US. In order to select the optimal option for the design and construction of the US, the results of economic and geological scenarios analysis were studied concurrently with the capabilities of the technological operation of the object and transport system, which can ensure the maximum daily production of the storage.

Improvement of the well cementing technology

“…In the course of experimental studies [4], it was determined that the composition for temporary blocking of the productive formation has a high adhesive ability (Figure 2a) and sufficient gel strength, which makes it possible to cut off the productive formation from the penetration of cement slurry during cementing and prevent the migration of formation gas into the hardening cement slurry solution during WOC (Figure 2b). To study the gel-forming composition for gas holding capacity and for contact strength with rock and metal, tests were carried out.…”

“…A noticeable expansion begins with an increase in the content of the additive in the dry mixture by more than 4 wt. % and recommended for filling the annulus [7]. The developed composition has low water separation and high sedimentation stability; has rheological parameters that meet the specified cementing conditions, short setting times, low gas permeability; strength characteristics of cement stone by the end of the WOC are 5-7 MPa in bending and 14-16 MPa in compression [8].…”

“…• In order to compensate for the decrease in bottomhole pressure during the WOC period due to the structure formation of the cement slurry, experimental studies were carried out, which are widely presented in the works [3,7,8].…”

Hydrodynamic Modeling and Evaluation of Partial Substitution of Cushion Gas During Creation of Temporary Underground Gas Storage in an Aquifer

“…The thermobaric conditions of the selected geological object and the component composition determine such characteristics of the injected gas as the supercompressibility coefficient, density, and viscosity. They also exert a significant impact on the completeness of displacement, the degree of gas mixing, and the volume of cushion gas (23). Calculation was performed for reservoir temperature 298,15 K.…”