Development of technological solutions for reliable killing of wells by temporarily blocking a productive formation under ALRP conditions (on the example of the Cenomanian gas deposits)

Abstract

Modern field operation conditions are characterized by a decline in gas production due to the depletion of its reserves, a decrease in reservoir pressure, an increase in water cut, as well as due to the depreciation of the operating well stock. These problems are especially specific at the late stage of development of the Cenomanian deposits of Western Siberia fields, where the anomaly factor below 0.2 prevails, while gas-bearing formations are represented mainly by complex reservoirs with high-permeability areas. When killing such wells, the classical reduction of overbalance by reducing the density of the process fluid does not provide the necessary efficiency, which requires the search for new technical and technological solutions. In order to prevent the destruction of the reservoir and preserve its reservoir properties during repair work in wells with abnormally low reservoir pressure, AO “SevKavNIPIgaz” developed compositions of special process fluids. A quantitative description of the process of blocking the bottomhole formation zone is proposed by means of mathematical modeling of injection of a gel-forming solution into a productive horizon. The well killing technology includes three main stages of work: leveling the injectivity profile of the productive strata using three-phase foam, pumping the blocking composition and its displacement with the creation of a calculated repression. Solutions obtained on the basis of a mathematical model allow optimizing technological parameters to minimize negative consequences in the well killing process.

Improvement of the well cementing technology, increasing the reliability of the annule isolation and preserving the permeability of the reservoir

“…In the course of experimental studies [2], 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.…”

Standards for Selection of Surfactant Compositions used in Completion and Stimulation Fluids

“…In addition to the electrostatic forces between water molecules and cations, osmotic swelling promotes the penetration of freely moving water molecules into the clay pores, depending on the concentration gradient [16]. All of these processes lead to the initiation of the swelling process.…”