Examples

Solotvyno and Dibrova gas fields,
Transcarpathian Trough,
Ukraine, 2005

Table 1. Drilling history and well testing results in Dibrova and Solotvyno gas fields

Both fields are located near Solotvyno salt diapir and are overlaid by salty beds of Tereblya formation. 

By 2D seismic data, Solotvyno and Dibrova gas pools occure in Neogene and Paleogene anticlinal structures respectively. Wells #4 and #22 of Dibrova field were placed in northern pericline of Dibrova anticline; wells #1 and #2 - in western pericline of Solotvyno anticline.

 Figure 1. The contour of gas-bearing pool in Paleogene of Dibrova field outlined by density value of 2.50 g/ccm. Dry wells №23 and №28 discovered dense impermeable rocks

Figure 2.The contour of gas-bearing pool in Neogene of Solotvyno field outlined by density value of 2.38 g/ccm. Producing well №15 discovered low-density gas-saturated rocks

GEOLOGICAL RESULTS

The shape of Solotvyno salt diapir was refined by results of 3D gravity inversion. It turned out that the bottom of salt body deeps over  2.5 km down while in the initial 3D model it reached only 1.3 km depth (Figure 3).

Paleogene gas-bearing pool of Dibrova field corresponds to low-density area outlined by maximum density value of 2.50 g/ccm. Producing wells #4 and #22 are located within the low-density anomaly (Figure 1). The most qualitative gas-saturated pools are developed to the south from wells #4 and #22 under Solotvyno salt diapir.

The rest of the anticlinal structure is characterized by dense sediments which indicates an absence of good reservoir rocks and hydrocarbon saturation. It was confirmed by dry wells #23 and #28 (Table 1).

Neogene gas-bearing pool of Solotvyno field corresponds to low-density area outlined by maximum density value of 2.38 g/ccm. Producing wells #1 and #2 are located within the low-density anomaly (Figure 2). Neogene gas-bearing pool is located in the apical and south-eastern part of Solotvyno anticline. Commercial gas inflow from well #15 within the apical part of the structure (Table 1) confirms validity of the outlined contour of Neogene gas-bearing pool in Solotvyno field.

Figure 3. Initial (а) and final (b) 3D density models

Figure 1. Observed (а) and calculated gravity fields in case of initial (b) and final (с) 3D density models and gravity misfit in case of initial (d) and final (e) 3D density models

PUBLICATIONS

1. Петровський О.П., Федченко Т.О. Нові напрями застосування даних акустичних досліджень в свердловинах для відновлення неоднорідної сейсмошвидкісної моделі середовища та сейсмо-стратиграфічного розчленування розрізу Солотвинської площі. Геоінформатика. 2006. - №3. - С.29-33 

2. Федченко Т.О.,  Петровский О.П. Пространственная информативность априорных геолого-геофизических данных и эффективность интегрального моделирования нефтегазо-перспективных объектов. Геофизический журнал. 2010. - №3. Т.32 - С.125-135

3. Fedchenko T. , Petrovskyy O., Trachuk A., Onyschuk O. Subsalt 3-D Modelling and HC Reservoir Prediction With Scarce 2-D Seismic Datasets: Can We Obtain Reliable Results? AAPG Annual Conference & Exhebition, Houston, on 02-05 April 2017, Poster presentation.