AGH DRILLING, OIL, GAS

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Przeglądanie AGH DRILLING, OIL, GAS według autora "Balázs, Sándor"

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    Identifying undrained layers from mature gas reservoirs using reservoir simulation and high resolution geophysical investigations
    (Wydawnictwa AGH, 2019) Tătaru, Argentina; Simescu, Ana Maria; Balázs, Sándor
    While big discoveries and major new developments deservedly grab the headlines, mature fields are the backbone of gas production. Revitalizing these fields extends their productive lives and offers significant opportunity to expand worldwide reserves. Regardless of the definition, mature fields are a huge resource. With reserves categorized as proved or probable, attempts to expand reserve levels come at a relatively low risk. Revitalizing a mature field means taking measures that increase the value extracted from the field beyond original expectation. Using specialized software brings new opportunities in reservoir simulation of mature gas reservoirs. Combining these simulations with high resolution geophysical investigations, will offer a other perspective about mature gas reservoirs as well as the identification of potentially gas bearing layers which in the first place were not been identified through logging, and in addition to a eventual growth of gas resources but also gas reserves that could be exploited. Identifying the thinest gas saturated layers, determine the modification of gas resources and reserves values. The increase of volumes is a result of larger production surfaces, larger net thicknesses and also larger porosity attributed to this zones. For mature gas reservoirs this kind of approach offers new perspectives.
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    Implementation of project management concept, in depleted gas reservoir exploitation
    (2015) Tătaru, Argentina; Ştefănescu, Dan-Paul; Balázs, Sándor
    In the past the gas industry focused its interest and major investments mainly on the early life of the reservoir and on the development and constant maintenance of production. But times change and currently for depleted gas reservoirs defined as reservoirs in an advanced stage of decline, energy and production should be considered as potential additional energy sources. The ideal time to start managing a reservoir is at its discovery, but Romgaz has a new approach regarding project management implemenatation for depleted gas fields. The strategy presumed, a multidisciplinary team of geophysicists, geologists, reservoir engineers, production engineers and economists. These multidisciplinary teams evaluated existing information and build up a plan for new data acquisitions, the data was integrated, processed, interpreted and correlated in a study with following objectives: - Construct 3D geological model to estimate resources. - Use reservoir engineering to estimate remaining reserves and expected ultimate recovery. - Use results of the study to identify new development opportunities on the field and forecast production scenarios. Success for this challenge depended on: - working as a team; - openness, flexibility, communication, and coordination; - persistence.
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    Mature gas fields rehabilitation concepts
    (2014) Tătaru, Argentina; Şuţoiu, Florinel; Balázs, Sándor
    Rehabilitation operations are applied to mature gas field, which although have a significant history production, owns a continuous energetical capacity which could be exploited in economicaly efficient conditions. For rehabilitation are selected from all the mature fields those which could additionally offer to the currently obtained basis production, a supplementary production, generated through interventions in reservoirs, wells or surface infrastructure. Although the opportunity of mature gas field rehabilitation is evident and unanimously accepted, the effective implementation of the concept represents a complex intervention. This fact is just due to natural gas reservoirs diversity, which involves developing particular models of rehabilitation, adapted to each reservoir capability. Conceptually, mature gas field rehabilitation can be divided in three sequences: reservoir, well, surface facilities. Intervention in one section or another, or concomitent intervention in all three sequences, is dictated by technical and economical reasons. Mature gas field rehabilitation must begin with main production problems identification that once recognized can be solved by remedial actions. Such corrective measures are commonly used in order to inerease the productivity of gas wells and removing restrietions on reservoir - well - surface facilities route.
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    Production decline curve analysis for mature gas reservoirs subject to rehabilitation
    (Wydawnictwa AGH, 2018) Tătaru, Argentina; Ştefănescu, Dan-Paul; Balázs, Sándor
    Production decline under all its aspects, sometimes controllable, but more and more inconsistent with the growing demands of the natural gas market, has imposed a new approach on mature gas reservoirs which Romania owns, namely, their rehabilitation. During exploitation, after recording a considerable production history and implicitly a appreciable depletion, it is necessary the evaluation of maintaining or changing the exploitation strategy. The approaches in this sense must be from the perspective of improving the value of mature gas fields. Throughout the exploitation of a gas reservoir generally there are distinquished several stages, such as gradually increase of gas flow rates due to increasing gas wells introduced into production, maintaining of a quasi-constant production, a accentuated decline of gas flow rates of the reservoir respectively a attenuated decline of gas flow rates of the reservoir. The first three stages are quite short reported to the whole exploitation process of the reservoir. The production decline appears sooner or later depending on the manifestation form of the reservoir energy. For the accuracy of the baseline which is to be established, can be taken in discussion, as reference intervals, those periods from the production history, in which the points dispersion is minimal, and flow rates respectively the production are comparable with the current ones. Taking into consideration the decline values obtained from decline curve analysis characteristically to every exploitation stage, we consider that to define the baseline production afferent to the next stage, it is optimal to accept the specific decline of the latest exploitation period. It can be noted that throughout production history, although the exploitation of the gas reservoir was intensified, due to accessing new reserve volumes, the decline tendency is to maintain at a limited interval. This behavior indicates the fact that also in conditions of intensifying the exploitation in the future, the decline will maintain a value sensitively close to the values from the latest periods, in which rehabilitation was applied.
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    Underbalanced interventions in gas wells belonging to mature gas fields
    (2017) Tătaru, Argentina; Balázs, Sándor; Foidaş, Ion
    The exploitation of natural gas fields from Transylvanian Basin started a century ago. The majority of these fields were discovered and developed in the last century, from the 1920s through the 1980s. So, these reservoirs have almost 100 years of production historical. Even if at their discovery, the initial reservoir pressures were relative high (around 100–150 bar), nowadays these mature gas fields have a very low reservoir pressure. For some of these reservoirs the pressure is 10–20% of initial values. With the rehabilitation projects ongoing, and where the challenge is to maintain or even better to increase by just a little the base production, the greatest challenge is to make certain interventions in depleted reservoirs wells. At the beginning it was not a problem to do workover for these wells because the completion fluids were lost in the reservoir and the reservoir pressures helped the wells to clean up. Now, because of the low reservoir pressures, after the interventions it would take a long time for the wells to be cleaned, or in the worst cases the wells could be abandoned. From time to time, some net pays have to be bypassed because the fluid can be lost in the reservoir. So the best method is to do workovers jobs in these wells underbalance or even with live well, and interventions using snnubing unit or the coiled tubing unit. This paper presents some of the technologies used by Romgaz to accomplish this goal and also some case studies from different types of interventions in these gas wells.