HomeWorkpackagesWorkpackages 2 - ResearchWP 2.05: Hydro-fracturing and acidizing

WP 2.05: Hydro-fracturing and acidizing

The main objective of WP 2.05 was to enhance productivity of geothermal wells by applying stimulation techniques (hydrofracturing, thermal fracturing and acidizing).

Drilling cost is a major expense for upstream development costs. Reduction of drilling cost has a significant impact to the economy of the project. Well productivity is a key parameter for upstream development cost efficiency. Productivity of geothermal well is controlled by reservoir transmissivity and skin factor. Furthermore a successful stimulation job secures the overall project economy.

Prior to implementing the stimulation job, we had to consider candidate selection due to the nature of the reservoir, well geometry and expected improvement. Along with the earlier consideration, the cost benefit analysis should be conducted to get insights about the feasibility of the activity. There are different methods to stimulate wells. All methods enhance the permeability of the reservoir around the well. The largest pressure drop in the reservoir takes place just around the well, so increasing the permeability in this region significantly impacts the productivity (and/or injectivity) of a well.

The available methods are:

Often combinations of the three methods are applied. The best type and method of stimulation depends on the local circumstances; when stimulating an existing well, also the status and design of the well will influence the choices that can be made.

Two master thesis implemented the scopes of this workpackage dealing with the thermal effect of fracturing on rock samples from typical Indonesian geothermal reservoir and with th acidizing.

Both thesis by Tulus Imaro (2017) and Prita Kandella Naymilton (2018) have been conducted in the geomechanical laboratories of TUD.

Additonal work has been dedicated to the collection of the rock samples used by for the experiments on regular field campaigns conducted during the lifetime of GEOCAP jointly with ITB and UGM. Localities such as Wayang Windu, Mount Salak and Flores have been visited in order to collect water and fluid samples. The most relevant results have been published in:

Deon et al. (2017) Hydrothermal alteration characterization of geothermal fields in Indonesia by rock petrology and modelling

Deon et al. (2018) Clays detection on hydrothermally altered samples: am method to apply in geothermal exploration in Indonesia.