Optimization of the utilization of deep borehole heat exchangers

Geothermal Energy

Science – Society – Technology

Table 1 The drilling cost of different borehole diameter intervals and rock types

Rock type	#1 (yuan/m)	#2 (yuan/m)	#3 (yuan/m)	#4 (yuan/m)	BHE depth (m)
Sandstone	1497	1599	2135	2393	500
Sandstone	2994	3198	4270	4786	1000
Sandstone	5988	6396	8540	9572	1500
Sandstone	8982	9594	12,810	14,358	2000
Sandstone	11,976	12,792	17,080	19,144	2500
Sandstone	17,964	19,188	25,620	28,716	3000
Limestone	2159	2374	3086	3450	500
Limestone	4318	4748	6172	6900	1000
Limestone	8636	9496	12,344	13,800	1500
Limestone	12,954	14,244	18,516	20,700	2000
Limestone	17,272	18,992	24,688	27,600	2500
Limestone	25,908	28,488	37,032	41,400	3000
Granite	3670	4036	5246	5865	500
Granite	7340	8072	10,492	11,730	1000
Granite	14,680	16,144	20,984	23,460	1500
Granite	22,020	24,216	31,476	35,190	2000
Granite	29,360	32,288	41,968	46,920	2500
Granite	44,040	48,432	62,952	70,380	3000