Developing features of the near-bottomhole zones in productive formations at fields with high gas saturation of formation oil

Abstract

The article studies the formation features of the bottomhole zones in productive formations during operation of production wells in the north of the Perm Territory. Their distinctive feature is the high gas saturation of formation oil. The most widely used parameter in Russian and world practice – the skin factor was used as a criterion characterizing the state of the bottomhole zone. Analysis of scientific publications has shown that one of the main problems of applying the skin factor to assess the state of bottomhole zones is the ambiguity of interpretations of its physical meaning and the impossibility of identifying the prevailing factors that form its value. The paper proposes an approach to identifying such factors in the conditions of the fields under consideration, based on multivariate correlation-regression analysis. Choice of this tool is due to the complexity of the processes occurring in the “formation – bottomhole zone – well” system. When describing complex multifactorial processes, the chosen method demonstrates a high degree of reliability. For a large number of wells in the region, significant material was collected and summarized, including the results of determining the skin factor (1102 values) during hydrodynamic investigations, as well as data on the values ​​of various geological and technological indicators, which can probably be statistically related to the value of the skin factor. A series of multidimensional mathematical models has been built; the skin factor was used as a predicted parameter, and data on the values ​​of geological and technological indicators were used as independent indicators. Analysis of the constructed models is a key stage of this study. Set of parameters included in the multidimensional models, sequence of their inclusion and contribution to the total value of the achieved determination coefficient as the main indicator for the performance of the constructed models were studied. It has been established that the main factor influencing the state of the bottomhole zone is oil degassing. Significant differences in the formation features of the skin factor in the terrigenous and carbonate sediments at the fields under consideration have been determined.

Gas–Liquid Flow Pattern and Hydrate Risk in Wellbore during the Deep-Water Gas-Well Cleanup Process

“…The heat transfer from the inside of the test string to the formation needs to overcome several thermal resistances, including liquid film thermal resistance, hydrate deposition layer thermal resistance, test string (tubing) thermal resistance, casing thermal resistance, cement ring thermal resistance, annulus radiation, and convection heat transfer resistance. The comprehensive thermal conductivity can be expressed as − U normala normalo = true[ r normalt normalo r normalt normali h normalf + r normalt normalo r normalt normali h normalh + r normalt normalo λ normalt normalu normalb ln nobreak0em.25em⁡ r normalt normalo r normalt normali + 1 h normalc + h normalr + r normalt normalo λ normalc normala normals ln nobreak0em.25em⁡ r normalc normalo r normalc normali + r normalt normalo λ normalc normale…”

“…The heat transfer from the inside of the test string to the formation needs to overcome several thermal resistances, including liquid film thermal resistance, hydrate deposition layer thermal resistance, test string (tubing) thermal resistance, casing thermal resistance, cement ring thermal resistance, annulus radiation, and convection heat transfer resistance. The comprehensive thermal conductivity can be expressed as − …”

Modeling Results for the Real Horizontal Heavy-Oil-Production Well of Mechanical Solids

“…Studies conducted in Russia and abroad demonstrate that during well development, testing, and operation, the solid particles drilled out of the bed are recovered due to destruction of natural cementing material therein. A non-cemented bed is considered to be a formation not containing a sufficient amount of natural cementing material in order to retain the composing rock of minerals in mutual contact during oil or gas inflow to the well [7,8].…”

Filtration studies on cores and sand packed tubes from the Urengoy field for determining the efficiency of simultaneous water and gas injection on formation when extracting condensate from low-pressure reservoirs and oil from oil rims

“…When studying the specific features of formation of bottomhole zones of oil pays during operation of producing wells at the fields in the northern Perm Region with high gas saturation of formation oil, an analysis of the skin factor was considered, and multidimensional mathematical models were built to determine the main factor affecting the state of bottomhole zones [58]. To increase the economic efficiency of hydrochloric acid treatment at the Chaikinskoye deposit in Perm Region, an algorithm was developed that can be implemented without difficulty using any programming language [59].…”