Effects of mineral composition and heterogeneity on the reservoir quality evolution with CO₂ intrusion

Abstract

During the diagenesis of rocks in a sedimentary basin, an intrusion of CO 2 could cause dissolution or/and precipitation of the surrounding rocks. As a result, the reservoir quality may be altered. The mineral composition and heterogeneity have pronounced impacts on the geochemical reaction and reservoir quality evolution. A numerical simulation method is employed to investigate the influences of primary mineral on the diagenesis. Based on the measured data from the Songliao Basin, a total of 26 two-dimensional models with different mineral composition are set up. To mimic the regionally heterogeneous distribution of mineral composition, the Monte Carlo method is employed. A CO 2 gas reservoir of magma intrusion origin, located in the Songliao Basin, northeastern China, is selected for the present study. The reservoir is an ideal site for investigating the impact of mineral heterogeneity on diagenesis after the CO 2 intrusion. In this reservoir, with the presence of high-pressure CO 2 , the mineral heterogeneity causes significant dissolution and precipitation of minerals, which decreases the reservoir porosity and degrades the reservoir quality. The geochemical reactions caused by different mineral composition vary widely. The mineral heterogeneity causes similar distributions of the geochemical reactions and reservoir quality evolution. Dominant secondary minerals are dawsonite in the early diagenesis and ankerite in the late stage. The diagenetic sequences modeled by our numerical simulations reproduce the petrographic and geochemical data well.

Rates of mineral dissolution under CO2 storage conditions

“…The pore space is filled with residually trapped sc-CO 2 surrounded by CO 2 -saturated water forming a low-pH environment. The magnitude of carbonate mineral trapping capacity is dependent on the formation water composition and the variety of reactive minerals within a reservoir (Gilfillan et al, 2009;Xu et al, 2005;Yang et al, 2014).…”

Effect of Temperature and Acidification on Reinjection of Geothermal Water into Sandstone Geothermal Reservoirs: Laboratory Study

“…Each geothermal field has a unique geological setting and reservoir characteristic [28][29][30]. It might be complicated to determine the "optimal" water reinjection [31,32], but the study of the effect of temperature and acidification on the water-rock interaction can provide a reference for reinjection of the sandstone geothermal reservoir.…”

Geochemical effects of cement mineral variations on water–rock–CO2 interactions in a sandstone reservoir as an experiment and modeling study

“…Similarly, Yang et al . found that ankerite and kaolinite will precipitate at the expense of chlorite and anorthite dissolution, when investigating the effects of primary mineral abundances on water–rock–CO 2 interaction by modeling . What is more, Choi et al .…”

“…6 Similarly, Yang et al found that ankerite and kaolinite will precipitate at the expense of chlorite and anorthite dissolution, when investigating the effects of primary mineral abundances on water-rock-CO 2 interaction by modeling. 7 What is more, Choi et al recorded the precipitation of siderite as a result of chlorite dissolution in a CO 2 injection model, and highlighted the stability of siderite, which is quite sensitive to the dissolution rate of chlorite. 8 Apart from the differences in mineral components, the in situ water chemistry also plays a key role in controlling the minerals' alteration.…”