An assessment of the effectiveness of drilling waste treatment process in X-gas field, Niger Delta, Nigeria

Figures & data

Table 1. Wastes components and environmentally significant constituents from drilling activities (adopted from Bashat, 2002).

Type of waste	Main components	Possible environmentally significant constituents
Waste lubricants	Lube oil, grease	Heavy metals, organics
Spacers	Mineral oil, detergents, surfactants	Hydrocarbon, alcohol, aromatics
Spent/Contaminated water-based muds (include brine)	Whole mud, mineral oil, biodegradable matters	Heavy metals, inorganic salts, biocides, hydrocarbons, solids/cutting, BOD, organics
Spent/Contaminated oil-based muds	Formation solids, water-based muds, mineral oil	Heavy metals, inorganic salts, biocides, hydrocarbons, solid/cutting
Oil-based muds cuttings	Whole mud mineral oil	Hydrocarbons, heavy metals, inorganic salts, solids, BOD, organics, surfactants
Spent bulk chemical	Cement, bentonite, barites, thinners, fluid loss reducers, specialty product	Heavy metals, hydrocarbon, organics, solids
Spent special products	H2S scavengers, defoamers, tracers	Zinc carbonates, iron oxides, hydrocarbons, silicon oils, potassium salts, radioactive material

Figure 1. Location map of the study area.

Figure 2. Geological map of the study area.

Figure 3. Arrows showing solid control units on drilling site.

Figure 4. Flocculation unit of the dewatering system.

Figure 5. Coagulation unit of dewatering system.

Figure 6. Flow chart of drilling waste management in X-Gas Field, Niger Delta Nigeria.

Table 2. Physiochemical analysis of drill cuttings at drilling point.

	Sampling depths (feet)
Parameter	1000	2000	3000	4000	5000	6000	7000	8000	9000	10,000	11,000	12,000	13,000	Average	DPR/FMENV limit
pH	10.6	10	10.9	10.1	10.7	12.3	9.77	12.1	11.94	9.67	10.5	11.06	10	10.742	6.5–8.5
Metals:
Cu (mg/l)	9.4	6.58	20.79	14.04	15.32	10.5	15.45	17.89	16.9	18.88	16.03	14.87	10.3	14.381	1.5
Pb (mg/l)	16.1	6.29	15.2	7.57	4.29	5.65	5.87	4.32	7.3	9.09	5.29	8.63	4.46	7.6969	0.05
Hg (mg/l)	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	0.2
Ni (mg/l)	39.3	50.9	21.39	16.5	32.89	43.36	38.2	49.26	19.33	35.41	45.56	37.39	22.8	34.792	–
Fe (mg/l)	13.4	10.4	16.98	15.3	17.3	16.54	13.36	19.81	16.03	17.67	16.31	15.38	16.63	15.778	1
V (mg/l)	22.4	15.6	19.06	28.6	20.5	13.89	16.58	19.5	22.05	16.83	28.3	16.38	25.38	20.39	–
Ba (mg/l)	62.9	57.9	25.09	101.3	69.06	89.55	20.35	56.51	52.6	57.29	77.61	64.6	57.89	60.973	100
Cr (mg/l)	<0.5	4.59	3.39	<0.5	2.2	5.33	2.63	3.38	4.08	2.51	3.07	2.39	4.67	3.4764	5

Bold values indicates the Average values

Table 3. Physiochemical analysis of drilling mud at drilling point.

	Sampling depths (feet)
Parameters	1000	2000	3000	4000	5000	6000	7000	8000	9000	10,000	11,000	12,000	13,000	Average	DPR/FMENV limit
pH	11.2	11	11.7	11.8	10.6	14.5	12.9	9.68	12	12.5	11.62	10.97	9.35	11.53	6.5–8.5
Cu (mg/l)	6.8	7.5	4.43	15.6	9.6	7.7	6.4	8.22	6.67	13	10.56	9.93	7.84	8.7885	1.5
Pb (mg/l)	7.22	4.93	5.05	6.3	3.64	4.8	3.59	4.8	3.47	4.32	4.62	3.58	3.14	4.5738	0.05
Hg (mg/l)	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	<0.01	0.2
Ni (mg/l)	16.8	22.53	14.29	10.6	14.11	12.85	12.93	16.93	14.39	15.01	10.3	16.4	14	14.703	–
Fe (mg/l)	5.57	11.4	9.25	9.45	16.8	11.29	10.6	15.19	11.35	13.2	13.13	10.96	10.65	11.449	1
V (mg/l)	15.9	10.1	14.82	13.03	17.53	12.7	14.37	12.78	14.37	19.11	19.3	17.56	11.24	14.832	–
Ba (mg/l)	106.4	58.7	45.8	97.02	69.06	35.41	54.57	50.03	30.51	28.35	40.03	39.38	48.19	54.112	100
Cr (mg/l)	<0.5	6.68	0.51	<0.03	<0.03	<0.03	<0.03	<0.03	<0.03	<0.03	<0.003	<0.003	<0.003	3.595	5

Bold values indicates the Average values

Table 4. Physiochemical analysis of waste from waste pit.

Parameters	1	2	3	4	5	6	7	8	9	10	11	12	Average	DPR/FMEnv limit
Temp. (°C)	33.1	30.2	30.3	30.9	36	34.3	31.9	32.8	34.6	35.7	34.7	31.2	32.98	25–35
Odor	O	O	O	O	O	O	O	O	UO	O	UO	O	O	UO
Turbidity (NTU)	1100	41	1815	2076	174	869	399	371	85	605	18	18	630.92	15
pH	6.3	6.4	6.2	5.9	6.1	7.2	6.8	9.1	7.3	6.7	7.4	6.9	6.86	6.5–8.5
EC (µS/cm) @ 25°C	5180	1772	12,700	27,200	10,250	2610	2340	5380	1607	8160	907	916	6585.17	–
TDS (mg/l)	2930	888	6380	14,610	5660	1326	1183	2380	663	3540	368	397	3360.42	2000
DO (mg/l)	0.45	1.28	1.42	0.38	0.37	0.97	0.53	0.87	3.95	0.76	2.31	1.83	1.26	–
Salinity mg/l	2130	462	3106	8875	3195	1065	1065	1331	364	2751	284	240	2072.33	600
TSS (mg/l)	>1.100	57	889	2845	192	1011	471	448	227	855	25	25	640.45	30
THC (mg/l)	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	0.9	10
BOD (mg/l)	43	15	423	613	520	389	241	108	43	133	12	–	230.91	10
COD (mg/l)	1131	62	1290	1700	1002	921	747	554	98	469	23	86	673.58	10
Heavy metals
Fe^2+ (mg/l)	0.52	1.24	1.2	1.72	1.37	1.2	1.4	2.73	1.52	0.39	0.26	0.44	1.17	1
Zn^2+ (mg/l)	0.38	0.61	0.5	0.24	0.41	0.58	0.44	0.56	0.58	0.43	0.44	0.22	0.45	1
Pb^+ (mg/l)	0.009	0.009	0.009	0.009	0.009	0.009	0.009	0.04	0.009	0.66	0.58	0.38	0.14	0.05
Cu^2+ (mg/l)	0.73	0.009	0.009	1.33	1	1.3	1.5	1.4	1.05	1.4	1.3	1.2	1.02	1.5
As^3= (mg/l)	0.09	0.09	0.049	0.009	0.009	0.009	0.049	0.049	0.009	0.009	0.009	0.009	0.03	–
Cr^3+ (mg/l)	0.004	0.009	0.009	0.0009	0.0009	0.0009	0.009	0.009	0.001	0.0009	0.0009	0.0009	0.003	0.03
Ba^2+ (mg/l)	2.47	1.32	0.46	2.5	1.64	1.53	2.3	1.58	1.4	2.3	2.2	2.3	1.83	–
Hg^2+ (mg/l)	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	0.029	–

Bold values indicates the Average values

Table 5. Results of analysis on sample after TDU operation.

Parameters	DPR max limit	Result
Moisture content (%)	<50% by Wt or zero-free	5.327
Ph	6–9	7.9
Electric conductivity (Mmhos/cm)	8.0	6.974
SAR	12.0	4.752
ESP	15%	2.09
Oil and grease (mg/l)	100	4.871
Chloride (mg/l)	5000	1527.32
Arsenics (mg/l)	5	Below detection limit of 0.001 of AAS
Barium (mg/l)	100	38
Cadmium (mg/l)	1	0.305
Total chromium (mg/l)	5	2.985
Lead (mg/l)	5	BDL
Mercury (mg/l)	0.2	BDL
Selenium (mg/l)	1	BDL
Silver (mg/l)	5	BDL
Nickel (mg/l)	1.0	BDL
Zinc (mg/l)	50	43.63
Vanadium (mg/l)	1	BDL

SAR: Sodium adsorption ratio; ESP: exchangeable sodium percentage.

Figure 7. pH concentration in the drill cuttings and mud.

Figure 8. Copper, lead, and nickel concentrations in the drill cuttings and mud.

Figure 9. THC, BOD, and COD concentrations of drilling waste pit samples.

Figure 10. Average values of analyzed parameters from X-Gas Field after TDU operations against DPR/FMEnv limit.

Table 6. Correlation matrix between physico-chemical parameters.

	Turbidity	pH	TDS	EC	DO	Salinity	TSS	THC	BOD	COD
Turbidity	1.1592
pH	0.2346	1.1592
TDS	0.0311	0.8296	1.1592
EC	0.0302	0.8412	−0.4876	1.1592
DO	0.1925	−0.3777	0.2455	−0.4684	1.1592
Salinity	0.0491	0.8094	−0.5018	0.9910	0.9903	1.1592
TSS	0.3279	0.8771	−0.3535	0.8799	0.8841	−0.4215	1.1592
THC	0.1867	0.2873	0.0373	0.3513	0.3649	−0.5926	0.3819	1.1592
BOD	0.2835	0.6115	−0.5172	0.7004	0.6775	−0.1255	0.6735	0.6078	1.1592
COD	0.8799	−0.4554	0.3909	−0.6479	−0.6507	0.4251	−0.6039	−0.3260	−0.4301	1.1592

Table 7. Correlation matrix between heavy metals.

	Fe^2+	Zn^2+	Pb^+	Cu^2+	As^3+	Cr^3+	Ba^2+	Hg^2+
Fe^2+	1.3544
Zn^2+	0.1657	1.3544
Pb^+	−0.1628	−0.6572	1.3544
Cu^2+	0.1122	0.0740	−0.3193	1.3544
As^3+	0.2872	0.1098	0.3016	−0.4249	1.3544
Cr^3+	−0.0214	0.4516	0.4292	−0.4329	−0.4648	1.3544
Ba^2+	0.2184	−0.3494	−0.6688	0.4064	0.6654	−0.1678	1.3544
Hg^2+	0.2248	0.3787	0.1705	0.0206	0.3873	−0.1437	0.1089	1.3544

Bashat, H. (2002). Managing waste in exploration and production activities of the petroleum industry. Environmental Advisor, SENV. 1, 1–37

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